backend/app/models/setting.rb

@@ -1,5 +1,8 @@
 class Setting < ApplicationRecord
   THEMES = ['system', 'light', 'dark'].freeze
+
+  # These remain in the typed settings schema to preserve existing backend
+  # work. The common `/users/settings` page currently surfaces only `theme`.
   AUTO_FETCH_MODES = ['auto', 'manual', 'off'].freeze
   WIKI_EDITOR_MODES = ['split', 'write', 'preview'].freeze
 

frontend/src/App.tsx

@@ -10,9 +10,14 @@ import DevModeWatermark from '@/components/DevModeWatermark'
 import RouteBlockerOverlay from '@/components/RouteBlockerOverlay'
 import TopNav from '@/components/TopNav'
 import DialogueProvider from '@/components/dialogues/DialogueProvider'
-import { UserSettingsProvider } from '@/components/users/UserSettingsProvider'
 import { Toaster } from '@/components/ui/toaster'
 import { apiPost, isApiError } from '@/lib/api'
+import {
+    applyClientAppearance,
+    fetchUserSettings,
+    getClientThemeMode,
+    seedClientThemeMode,
+} from '@/lib/settings'
 import DeerjikistDetailPage from '@/pages/deerjikists/DeerjikistDetailPage'
 import MaterialBasePage from '@/pages/materials/MaterialBasePage'
 import MaterialDetailPage from '@/pages/materials/MaterialDetailPage'
@@ -105,6 +110,19 @@ const App: FC = () => {
   const [user, setUser] = useState<User | null> (null)
   const [status, setStatus] = useState (200)
 
+  useEffect (() => {
+    applyClientAppearance ()
+
+    const mediaQuery = window.matchMedia ('(prefers-color-scheme: dark)')
+    const handleThemeChange = () => {
+      if (getClientThemeMode () === 'system')
+	applyClientAppearance ()
+    }
+
+    mediaQuery.addEventListener ('change', handleThemeChange)
+    return () => mediaQuery.removeEventListener ('change', handleThemeChange)
+  }, [])
+
   useEffect (() => {
     const createUser = async () => {
       const data = await apiPost<{ code: string; user: User }> ('/users')
@@ -138,6 +156,23 @@ const App: FC = () => {
       createUser ()
   }, [])
 
+  useEffect (() => {
+    if (!(user))
+      return
+
+    void (async () => {
+      try
+      {
+	const settings = await fetchUserSettings ()
+	seedClientThemeMode (settings.theme)
+	applyClientAppearance ()
+      }
+      catch
+      {
+      }
+    }) ()
+  }, [user])
+
   switch (status)
   {
   case 503:
@@ -146,7 +181,6 @@ const App: FC = () => {
 
   return (
       <>
-	<UserSettingsProvider user={user}>
 	<RouteBlockerOverlay/>
 	{import.meta.env.DEV && <DevModeWatermark/>}
 
@@ -165,7 +199,6 @@ const App: FC = () => {
 	    <Toaster/>
 	  </DialogueProvider>
 	</BrowserRouter>
-	</UserSettingsProvider>
       </>)
 }
 

frontend/src/components/TagLink.tsx

@@ -1,9 +1,8 @@
 import PrefetchLink from '@/components/PrefetchLink'
 import ResponsiveMarqueeText from '@/components/ResponsiveMarqueeText'
-import { LIGHT_COLOUR_SHADE, DARK_COLOUR_SHADE, TAG_COLOUR } from '@/consts'
 import { cn } from '@/lib/utils'
 
-import type { ComponentProps, FC, HTMLAttributes } from 'react'
+import type { ComponentProps, CSSProperties, FC, HTMLAttributes } from 'react'
 
 import type { Tag } from '@/types'
 
@@ -36,15 +35,16 @@ const TagLink: FC<Props> = ({ tag,
 			      withWiki  = true,
 			      withCount = true,
 			      className,
+			      style,
 			      title,
 			      ...props }) => {
-  const spanClass = cn (
+  const colourStyle = {
-      `text-${ TAG_COLOUR[tag.category] }-${ LIGHT_COLOUR_SHADE }`,
+      '--tag-link-colour': `var(--tag-colour-${ tag.category })`,
-      `dark:text-${ TAG_COLOUR[tag.category] }-${ DARK_COLOUR_SHADE }`)
+      '--tag-link-hover-colour': `var(--tag-colour-${ tag.category }-hover)`,
-  const linkClass = cn (
+      ...style,
-      spanClass,
+  } as CSSProperties
-      `hover:text-${ TAG_COLOUR[tag.category] }-${ LIGHT_COLOUR_SHADE - 200 }`,
+  const spanClass = 'tag-link-colour'
-      `dark:hover:text-${ TAG_COLOUR[tag.category] }-${ DARK_COLOUR_SHADE - 200 }`)
+  const linkClass = 'tag-link-colour tag-link-hover-colour'
   const textClass = 'group min-w-0 max-w-full overflow-hidden align-bottom'
   const rootClass =
       'inline-flex min-w-0 max-w-full flex-nowrap items-stretch align-baseline gap-x-1 md:items-baseline'
@@ -63,7 +63,8 @@ const TagLink: FC<Props> = ({ tag,
 		  ? (
 		      <PrefetchLink
 			  to={`/wiki/${ encodeURIComponent (tag.name) }`}
-			  className={linkClass}>
+			  className={linkClass}
+			  style={colourStyle}>
 			?
 		      </PrefetchLink>)
 		  : (
@@ -71,13 +72,15 @@ const TagLink: FC<Props> = ({ tag,
 		      ? (
 			  <PrefetchLink
 			      to={`/materials/${ tag.materialId }`}
-			      className={linkClass}>
+			      className={linkClass}
+			      style={colourStyle}>
 			    ?
 			  </PrefetchLink>)
 		      : (
 			  <PrefetchLink
 			      to={`/tags/${ tag.id }/deerjikists`}
-			      className={linkClass}>
+			      className={linkClass}
+			      style={colourStyle}>
 			    ?
 			  </PrefetchLink>)))
 	       : (
@@ -120,6 +123,7 @@ const TagLink: FC<Props> = ({ tag,
 	      <span
 		  title={textTitle}
 		  className={cn (spanClass, textClass, className)}
+		  style={colourStyle}
 		  {...props}>
 		<ResponsiveMarqueeText
 		    text={tag.matchedAlias}
@@ -134,6 +138,7 @@ const TagLink: FC<Props> = ({ tag,
 		to={`/posts?${ (new URLSearchParams ({ tags: tag.name })).toString () }`}
 		title={textTitle}
 		className={cn (linkClass, textClass, className)}
+		style={colourStyle}
 		{...props}>
 	      <ResponsiveMarqueeText
 		  text={tag.name}
@@ -144,6 +149,7 @@ const TagLink: FC<Props> = ({ tag,
 	    <span
 		  title={textTitle}
 		  className={cn (spanClass, textClass, className)}
+		  style={colourStyle}
 		  {...props}>
 	      <ResponsiveMarqueeText
 		  text={tag.name}

frontend/src/components/common/TabGroup.tsx

@@ -7,12 +7,15 @@ type TabProps = { name:     string
 		  init?:    boolean
 		  children: React.ReactNode }
 
-type Props = { children: React.ReactNode }
+type Props = {
+    children:    React.ReactNode
+    rightAddon?: React.ReactNode
+}
 
 export const Tab = ({ children }: TabProps) => <>{children}</>
 
 
-const TabGroup: FC<Props> = ({ children }) => {
+const TabGroup: FC<Props> = ({ children, rightAddon }) => {
   const tabs = React.Children.toArray (children) as React.ReactElement<TabProps>[]
 
   const [current, setCurrent] = useState<number> (() => {
@@ -22,7 +25,8 @@ const TabGroup: FC<Props> = ({ children }) => {
 
   return (
       <div className="mt-4">
-	<div className="flex gap-4">
+	<div className="flex items-center justify-between gap-4">
+	  <div className="flex min-w-0 gap-4">
 	    {tabs.map ((tab, i) => (
 		<a key={i}
 		   href="#"
@@ -34,6 +38,11 @@ const TabGroup: FC<Props> = ({ children }) => {
 		  {tab.props.name}
 		</a>))}
 	  </div>
+	  {rightAddon && (
+	      <div className="shrink-0">
+		{rightAddon}
+	      </div>)}
+	</div>
 	<div className="mt-2">
 	  {tabs[current]}
 	</div>

frontend/src/components/users/UserSettingsProvider.tsx

@@ -1,6 +1,10 @@
 import { createContext, useContext, useEffect, useMemo, useState } from 'react'
 
-import { DEFAULT_USER_SETTINGS, fetchUserSettings } from '@/lib/settings'
+import {
+    applyClientAppearance,
+    DEFAULT_USER_SETTINGS,
+    fetchUserSettings,
+} from '@/lib/settings'
 
 import type { Dispatch, FC, ReactNode, SetStateAction } from 'react'
 
@@ -16,29 +20,6 @@ type ContextValue = {
 const UserSettingsContext = createContext<ContextValue | null> (null)
 
 
-const applyTheme = (theme: UserSettings['theme']) => {
-  const root = document.documentElement
-  const media = window.matchMedia ('(prefers-color-scheme: dark)')
-
-  const sync = () => {
-    const dark = theme === 'dark' || (theme === 'system' && media.matches)
-    root.classList.toggle ('dark', dark)
-    root.style.colorScheme = dark ? 'dark' : 'light'
-  }
-
-  sync ()
-
-  if (theme !== 'system')
-    return () => { }
-
-  const onChange = () => sync ()
-  media.addEventListener ('change', onChange)
-  return () => {
-    media.removeEventListener ('change', onChange)
-  }
-}
-
-
 export const UserSettingsProvider: FC<{
     children:  ReactNode
     user:      User | null }> = ({ children, user }) => {
@@ -87,7 +68,10 @@ export const UserSettingsProvider: FC<{
     }
   }, [user])
 
-  useEffect (() => applyTheme (settings.theme), [settings.theme])
+  useEffect (() => {
+    void settings.theme
+    applyClientAppearance ()
+  }, [settings.theme])
 
   const value = useMemo<ContextValue> (() => ({
       error,

frontend/src/index.css

@@ -29,6 +29,21 @@
     --border: 214.3 31.8% 91.4%;
     --input: 214.3 31.8% 91.4%;
     --ring: 222.2 84% 4.9%;
+
+    --tag-colour-deerjikist: #9f1239;
+    --tag-colour-deerjikist-hover: #b62a51;
+    --tag-colour-meme: #6b21a8;
+    --tag-colour-meme-hover: #8238bf;
+    --tag-colour-character: #4d7c0f;
+    --tag-colour-character-hover: #649326;
+    --tag-colour-general: #155e75;
+    --tag-colour-general-hover: #2c758c;
+    --tag-colour-material: #c2410c;
+    --tag-colour-material-hover: #d95823;
+    --tag-colour-meta: #a16207;
+    --tag-colour-meta-hover: #b8791e;
+    --tag-colour-nico: #4b5563;
+    --tag-colour-nico-hover: #626c7a;
   }
 
   .dark
@@ -161,6 +176,16 @@ body
   position: relative;
 }
 
+.tag-link-colour
+{
+  color: var(--tag-link-colour);
+}
+
+.tag-link-hover-colour:hover
+{
+  color: var(--tag-link-hover-colour) !important;
+}
+
 .tag-marquee__animated
 {
   position: absolute;

frontend/src/lib/settings.ts

@@ -1,10 +1,27 @@
+import { CATEGORIES } from '@/consts'
 import { apiGet, apiPatch } from '@/lib/api'
 
-import type { FetchPostsOrder, FetchTagsOrder } from '@/types'
+import type { Category, FetchPostsOrder, FetchTagsOrder } from '@/types'
 
-// DB-backed user settings. These are the cross-device preferences worth syncing.
 export type UserSettings = {
-    theme: 'system' | 'light' | 'dark' }
+    theme:               'system' | 'light' | 'dark'
+    autoFetchTitle:      'auto' | 'manual' | 'off'
+    autoFetchThumbnail:  'auto' | 'manual' | 'off'
+    wikiEditorMode:      'split' | 'write' | 'preview' }
+
+export type ThemeTagColours = Record<Category, string>
+export type BuiltinThemeId = 'light' | 'dark'
+export type ThemeId = BuiltinThemeId | `custom:${ string }`
+export type ActiveThemeId = ThemeId | 'system'
+export type ResolvedTheme = 'light' | 'dark'
+export type ClientTheme = {
+    id:         ThemeId
+    name:       string
+    builtin:    boolean
+    baseTheme:  BuiltinThemeId
+    tagColours: ThemeTagColours }
+export type CustomClientTheme =
+    ClientTheme & { builtin: false }
 
 export type TheatreLayoutMode = 'threeColumns' | 'tagsBottom' | 'commentsBottom'
 export type TheatreTagFlow = 'vertical' | 'horizontal'
@@ -21,14 +38,27 @@ type ClientListSettings = {
     limit?: ClientListLimit
     order?: string }
 
-type ClientKeyboardSettings = {
+export type ClientAppearanceSettings = {
-    shortcutsEnabled?: boolean }
+    activeThemeId?: ActiveThemeId
+    customThemes?:  Record<string, CustomClientTheme>
+    // Legacy fields kept for migration from the earlier appearance model.
+    theme?:         UserSettings['theme']
+    tagColours?:    Partial<ThemeTagColours> }
 
-// Browser-local settings. These stay device-specific and are not synced to DB.
+// DB-backed settings. At present only `theme` is surfaced in `/users/settings`.
+// The remaining fields are retained for existing backend work and are not wired
+// to the common settings UI yet.
+export const DEFAULT_USER_SETTINGS: UserSettings = {
+    theme:               'system',
+    autoFetchTitle:      'manual',
+    autoFetchThumbnail:  'manual',
+    wikiEditorMode:      'split' }
+
+// Browser-local settings only. These are device or screen specific.
 export type ClientSettings = {
+    appearance?:    ClientAppearanceSettings
     panes?:         Record<string, ClientPaneSettings>
     lists?:         Partial<Record<ClientListKey, ClientListSettings>>
-    keyboard?:       ClientKeyboardSettings
     theatre?:       {
 	layoutMode?: TheatreLayoutMode
 	tagFlow?:    TheatreTagFlow
@@ -41,9 +71,6 @@ export type ClientSettings = {
     thumbnailMode?: string }
 
 export const CLIENT_SETTINGS_STORAGE_KEY = 'btrc_hub.client_settings'
-export const DEFAULT_USER_SETTINGS: UserSettings = {
-    theme: 'system' }
-
 export const THEME_OPTIONS = ['system', 'light', 'dark'] as const
 export const LIST_LIMIT_OPTIONS = [20, 50, 100] as const
 export const POST_LIST_ORDER_OPTIONS = [
@@ -72,21 +99,84 @@ export const TAG_LIST_ORDER_OPTIONS = [
 ] as const satisfies readonly FetchTagsOrder[]
 export const DEFAULT_POST_LIST_LIMIT: ClientListLimit = 20
 export const DEFAULT_POST_LIST_ORDER: FetchPostsOrder = 'original_created_at:desc'
-export const DEFAULT_TAG_LIST_ORDER: FetchTagsOrder = 'name:asc'
+export const DEFAULT_TAG_LIST_ORDER: FetchTagsOrder = 'post_count:desc'
+export const DEFAULT_LIGHT_THEME_TAG_COLOURS: ThemeTagColours = {
+    deerjikist: '#9f1239',
+    meme:       '#6b21a8',
+    character:  '#4d7c0f',
+    general:    '#155e75',
+    material:   '#c2410c',
+    meta:       '#a16207',
+    nico:       '#4b5563',
+}
+export const DEFAULT_DARK_THEME_TAG_COLOURS: ThemeTagColours = {
+    deerjikist: '#fb7185',
+    meme:       '#d8b4fe',
+    character:  '#bef264',
+    general:    '#67e8f9',
+    material:   '#fdba74',
+    meta:       '#fde047',
+    nico:       '#e5e7eb',
+}
+export const DEFAULT_THEME_TAG_COLOURS = DEFAULT_LIGHT_THEME_TAG_COLOURS
+export const BUILTIN_THEMES: Record<BuiltinThemeId, ClientTheme> = {
+    light: {
+	id:         'light',
+	name:       'ライト・モード',
+	builtin:    true,
+	baseTheme:  'light',
+	tagColours: DEFAULT_LIGHT_THEME_TAG_COLOURS,
+    },
+    dark: {
+	id:         'dark',
+	name:       'ダーク・モード',
+	builtin:    true,
+	baseTheme:  'dark',
+	tagColours: DEFAULT_DARK_THEME_TAG_COLOURS,
+    },
+}
 
 const LEGACY_THEATRE_LAYOUT_STORAGE_KEY = 'theatre-layout-mode'
 const LEGACY_THEATRE_TAG_FLOW_STORAGE_KEY = 'theatre-tag-flow'
 const LEGACY_GEKANATOR_BACKGROUND_MOTION_STORAGE_KEY =
     'gekanator:background-motion:v1'
+const LEGACY_MIGRATED_THEME_ID = 'custom:legacy-migrated'
 
 
-export const fetchUserSettings = async (): Promise<UserSettings> =>
+export const fetchUserSettings = async (): Promise<UserSettings> => {
-    await apiGet<UserSettings> ('/users/settings')
+  const raw = await apiGet<{
+      theme:               UserSettings['theme']
+      auto_fetch_title:      UserSettings['autoFetchTitle']
+      auto_fetch_thumbnail:  UserSettings['autoFetchThumbnail']
+      wiki_editor_mode:      UserSettings['wikiEditorMode']
+  }> ('/users/settings')
+
+  return {
+      theme:               raw.theme,
+      autoFetchTitle:      raw.auto_fetch_title,
+      autoFetchThumbnail:  raw.auto_fetch_thumbnail,
+      wikiEditorMode:      raw.wiki_editor_mode,
+  }
+}
 
 
 export const updateUserSettings = async (
     settings: Partial<{ theme: UserSettings['theme'] }>,
-): Promise<UserSettings> => await apiPatch<UserSettings> ('/users/settings', settings)
+): Promise<UserSettings> => {
+  const raw = await apiPatch<{
+      theme:               UserSettings['theme']
+      auto_fetch_title:      UserSettings['autoFetchTitle']
+      auto_fetch_thumbnail:  UserSettings['autoFetchThumbnail']
+      wiki_editor_mode:      UserSettings['wikiEditorMode']
+  }> ('/users/settings', settings)
+
+  return {
+      theme:               raw.theme,
+      autoFetchTitle:      raw.auto_fetch_title,
+      autoFetchThumbnail:  raw.auto_fetch_thumbnail,
+      wikiEditorMode:      raw.wiki_editor_mode,
+  }
+}
 
 
 const safeParseClientSettings = (raw: string | null): ClientSettings => {
@@ -127,6 +217,365 @@ const validListLimit = (value: unknown): ClientListLimit | null =>
     value === 20 || value === 50 || value === 100 ? value : null
 
 
+const normaliseHexColour = (value: string): string | null =>
+    /^#[0-9a-fA-F]{6}$/.test (value) ? value.toLowerCase () : null
+
+
+const isBuiltinThemeId = (value: string): value is BuiltinThemeId =>
+    value === 'light' || value === 'dark'
+
+
+const isCustomThemeId = (value: string): value is `custom:${ string }` =>
+    value.startsWith ('custom:')
+
+
+const themeCopyName = (baseTheme: BuiltinThemeId): string =>
+    `${ BUILTIN_THEMES[baseTheme].name }のコピー`
+
+
+const appearanceFromSettings = (): ClientAppearanceSettings =>
+    loadClientSettings ().appearance ?? { }
+
+
+export const hasStoredClientThemeSelection = (): boolean => {
+  const appearance = appearanceFromSettings ()
+  return (
+      appearance.activeThemeId != null
+      || appearance.customThemes != null
+      || appearance.theme != null
+      || appearance.tagColours != null
+  )
+}
+
+
+const mixHexColour = (
+    source:  string,
+    target:  string,
+    ratio:   number,
+): string => {
+  const clampedRatio = Math.max (0, Math.min (1, ratio))
+  const src = source.slice (1)
+  const dst = target.slice (1)
+  const channels = [0, 2, 4].map (offset => {
+      const srcValue = parseInt (src.slice (offset, offset + 2), 16)
+      const dstValue = parseInt (dst.slice (offset, offset + 2), 16)
+      const mixed = Math.round (
+	  srcValue + (dstValue - srcValue) * clampedRatio,
+      )
+      return mixed.toString (16).padStart (2, '0')
+  })
+
+  return `#${ channels.join ('') }`
+}
+
+
+export const getClientThemeMode = (): UserSettings['theme'] =>
+    (() => {
+      const appearance = appearanceFromSettings ()
+      const customThemes = getClientCustomThemes ()
+
+      if (appearance.activeThemeId === 'system')
+	return 'system'
+      if (appearance.activeThemeId === 'light' || appearance.activeThemeId === 'dark')
+	return appearance.activeThemeId
+      if (
+	  typeof appearance.activeThemeId === 'string'
+	  && customThemes[appearance.activeThemeId] != null
+      )
+	return customThemes[appearance.activeThemeId].baseTheme
+
+      return appearance.theme ?? DEFAULT_USER_SETTINGS.theme
+    }) ()
+
+
+export const setClientThemeMode = (theme: UserSettings['theme']): void => {
+  updateClientSettings (settings => ({
+      ...settings,
+      appearance: {
+	  ...(settings.appearance ?? { }),
+	  activeThemeId: theme,
+	  theme,
+      },
+  }))
+}
+
+
+export const seedClientThemeMode = (theme: UserSettings['theme']): void => {
+  if (hasStoredClientThemeSelection ())
+    return
+
+  setClientThemeMode (theme)
+}
+
+
+const prefersDarkTheme = (): boolean =>
+    window.matchMedia ('(prefers-color-scheme: dark)').matches
+
+
+export const resolveThemeMode = (
+    theme: UserSettings['theme'],
+): ResolvedTheme =>
+    theme === 'system'
+    ? (prefersDarkTheme () ? 'dark' : 'light')
+    : theme
+
+
+export const defaultThemeTagColoursFor = (
+    theme: ResolvedTheme,
+): ThemeTagColours =>
+    theme === 'dark'
+    ? DEFAULT_DARK_THEME_TAG_COLOURS
+    : DEFAULT_LIGHT_THEME_TAG_COLOURS
+
+
+const normaliseThemeTagColours = (
+    input:     Partial<ThemeTagColours> | null | undefined,
+    fallback:  ThemeTagColours,
+): ThemeTagColours =>
+    CATEGORIES.reduce<ThemeTagColours> (
+	(colours, category) => {
+	    const candidate = input?.[category]
+	    colours[category] =
+		typeof candidate === 'string' && normaliseHexColour (candidate) != null
+		? candidate
+		: fallback[category]
+	    return colours
+	},
+	{ ...fallback },
+    )
+
+
+const normaliseCustomTheme = (
+    rawTheme:    unknown,
+): CustomClientTheme | null => {
+  if (!(rawTheme) || typeof rawTheme !== 'object')
+    return null
+
+  const theme = rawTheme as Record<string, unknown>
+  const id = typeof theme.id === 'string' ? theme.id : null
+  const name = typeof theme.name === 'string' ? theme.name : null
+  const baseTheme = typeof theme.baseTheme === 'string' ? theme.baseTheme : null
+  if (
+      id == null
+      || !(isCustomThemeId (id))
+      || name == null
+      || baseTheme == null
+      || !(isBuiltinThemeId (baseTheme))
+  )
+    return null
+
+  return {
+      id,
+      name,
+      builtin: false,
+      baseTheme,
+      tagColours: normaliseThemeTagColours (
+	  theme.tagColours as Partial<ThemeTagColours> | undefined,
+	  defaultThemeTagColoursFor (baseTheme),
+      ),
+  }
+}
+
+
+export const getClientCustomThemes = (): Record<string, CustomClientTheme> => {
+  const appearance = appearanceFromSettings ()
+  const customThemes = appearance.customThemes
+
+  if (customThemes && typeof customThemes === 'object')
+    {
+      return Object.entries (customThemes).reduce<Record<string, CustomClientTheme>> (
+	  (themes, [key, rawTheme]) => {
+	      const theme = normaliseCustomTheme (rawTheme)
+	      if (theme != null)
+		themes[key] = theme
+	      return themes
+	  },
+	  { },
+      )
+    }
+
+  const legacyTagColours = appearance.tagColours
+  if (!(legacyTagColours) || Object.keys (legacyTagColours).length === 0)
+    return { }
+
+  const baseTheme = resolveThemeMode (appearance.theme ?? DEFAULT_USER_SETTINGS.theme)
+  return {
+      [LEGACY_MIGRATED_THEME_ID]: {
+	  id: LEGACY_MIGRATED_THEME_ID,
+	  name: themeCopyName (baseTheme),
+	  builtin: false,
+	  baseTheme,
+	  tagColours: normaliseThemeTagColours (
+	      legacyTagColours,
+	      defaultThemeTagColoursFor (baseTheme),
+	  ),
+      },
+  }
+}
+
+
+export const getClientActiveThemeId = (): ActiveThemeId => {
+  const appearance = appearanceFromSettings ()
+  const customThemes = getClientCustomThemes ()
+
+  if (
+      typeof appearance.activeThemeId === 'string'
+      && (
+	  appearance.activeThemeId === 'system'
+	  || isBuiltinThemeId (appearance.activeThemeId)
+	  || customThemes[appearance.activeThemeId] != null
+      )
+  )
+    return appearance.activeThemeId
+
+  if (
+      Object.keys (customThemes).length > 0
+      && appearance.tagColours != null
+      && Object.keys (appearance.tagColours).length > 0
+  )
+    return LEGACY_MIGRATED_THEME_ID
+
+  if (typeof appearance.theme === 'string' && (
+      appearance.theme === 'system'
+      || appearance.theme === 'light'
+      || appearance.theme === 'dark'
+  ))
+    return appearance.theme
+
+  return DEFAULT_USER_SETTINGS.theme
+}
+
+
+export const getThemeById = (
+    themeId:       ThemeId,
+    customThemes:  Record<string, CustomClientTheme>,
+): ClientTheme =>
+    isBuiltinThemeId (themeId)
+    ? BUILTIN_THEMES[themeId]
+    : (customThemes[themeId] ?? BUILTIN_THEMES.light)
+
+
+export const getResolvedThemeFromSelection = (
+    activeThemeId: ActiveThemeId,
+    customThemes:  Record<string, CustomClientTheme>,
+): ClientTheme =>
+    activeThemeId === 'system'
+    ? BUILTIN_THEMES[resolveThemeMode ('system')]
+    : getThemeById (activeThemeId, customThemes)
+
+
+export const deriveUserThemeModeFromSelection = (
+    activeThemeId: ActiveThemeId,
+    customThemes:  Record<string, CustomClientTheme>,
+): UserSettings['theme'] => {
+  if (activeThemeId === 'system')
+    return 'system'
+
+  return getThemeById (activeThemeId, customThemes).baseTheme
+}
+
+
+export const createCustomThemeFromBase = (
+    baseTheme:   BuiltinThemeId,
+    tagColours?: ThemeTagColours,
+): CustomClientTheme => {
+  const id = `custom:${ crypto.randomUUID () }` as ThemeId
+  return {
+      id,
+      name: themeCopyName (baseTheme),
+      builtin: false,
+      baseTheme,
+      tagColours: tagColours ?? { ...defaultThemeTagColoursFor (baseTheme) },
+  }
+}
+
+
+export const getClientThemeTagColours = (
+    activeThemeId: ActiveThemeId = getClientActiveThemeId (),
+    customThemes:  Record<string, CustomClientTheme> = getClientCustomThemes (),
+): ThemeTagColours => {
+  return {
+      ...getResolvedThemeFromSelection (activeThemeId, customThemes).tagColours,
+  }
+}
+
+
+export const setClientAppearanceThemes = (
+    activeThemeId: ActiveThemeId,
+    customThemes:  Record<string, CustomClientTheme>,
+): void => {
+  updateClientSettings (settings => ({
+      ...settings,
+      appearance: {
+	  ...(settings.appearance ?? { }),
+	  activeThemeId,
+	  customThemes,
+	  theme: undefined,
+	  tagColours: undefined,
+      },
+  }))
+}
+
+
+export const setClientThemeTagColours = (
+    tagColours:     ThemeTagColours,
+    activeThemeId:  ActiveThemeId = getClientActiveThemeId (),
+    customThemes:   Record<string, CustomClientTheme> = getClientCustomThemes (),
+): void => {
+  if (activeThemeId === 'system' || isBuiltinThemeId (activeThemeId))
+    return
+
+  setClientAppearanceThemes (
+      activeThemeId,
+      {
+	  ...customThemes,
+	  [activeThemeId]: {
+	      ...customThemes[activeThemeId],
+	      tagColours,
+	  },
+      },
+  )
+}
+
+
+export const applyThemeMode = (theme: UserSettings['theme']): void => {
+  const root = document.documentElement
+  const resolvedTheme = resolveThemeMode (theme)
+
+  root.classList.toggle ('dark', resolvedTheme === 'dark')
+  root.style.colorScheme = resolvedTheme
+}
+
+
+export const applyThemeTagColours = (tagColours: ThemeTagColours): void => {
+  const root = document.documentElement
+
+  CATEGORIES.forEach (category => {
+      const colour = tagColours[category]
+      root.style.setProperty (`--tag-colour-${ category }`, colour)
+      root.style.setProperty (
+	  `--tag-colour-${ category }-hover`,
+	  mixHexColour (colour, '#ffffff', .18),
+      )
+  })
+}
+
+
+export const applyThemeSelection = (
+    activeThemeId: ActiveThemeId,
+    customThemes:  Record<string, CustomClientTheme>,
+): void => {
+  const theme = getResolvedThemeFromSelection (activeThemeId, customThemes)
+  applyThemeMode (theme.baseTheme)
+  applyThemeTagColours (theme.tagColours)
+}
+
+
+export const applyClientAppearance = (): void => {
+  applyThemeSelection (getClientActiveThemeId (), getClientCustomThemes ())
+}
+
+
 export const getClientListLimit = (
     listKey: ClientListKey,
 ): ClientListLimit | null => {
@@ -162,20 +611,6 @@ export const setClientListSettings = (
 }
 
 
-export const getClientKeyboardShortcutsEnabled = (): boolean =>
-    loadClientSettings ().keyboard?.shortcutsEnabled ?? true
-
-
-export const setClientKeyboardShortcutsEnabled = (
-    enabled: boolean,
-): void => {
-  updateClientSettings (settings => ({
-      ...settings,
-      keyboard: { ...(settings.keyboard ?? { }), shortcutsEnabled: enabled },
-  }))
-}
-
-
 const legacyTheatreLayoutMode = (): TheatreLayoutMode | null => {
   const value = localStorage.getItem (LEGACY_THEATRE_LAYOUT_STORAGE_KEY)
   return (

frontend/src/pages/posts/PostListPage.tsx

@@ -7,7 +7,6 @@ import PostList from '@/components/PostList'
 import PrefetchLink from '@/components/PrefetchLink'
 import TagSidebar from '@/components/TagSidebar'
 import WikiBody from '@/components/WikiBody'
-import FormField from '@/components/common/FormField'
 import Pagination from '@/components/common/Pagination'
 import TabGroup, { Tab } from '@/components/common/TabGroup'
 import MainArea from '@/components/layout/MainArea'
@@ -16,43 +15,21 @@ import { fetchPosts } from '@/lib/posts'
 import { postsKeys } from '@/lib/queryKeys'
 import {
     DEFAULT_POST_LIST_LIMIT,
-    DEFAULT_POST_LIST_ORDER,
     getClientListLimit,
-    getClientListOrder,
     LIST_LIMIT_OPTIONS,
-    POST_LIST_ORDER_OPTIONS,
     setClientListSettings,
 } from '@/lib/settings'
-import { inputClass } from '@/lib/utils'
 import { fetchWikiPageByTitle } from '@/lib/wiki'
 
 import type { FC } from 'react'
 
-import type { FetchPostsOrder, WikiPage } from '@/types'
+import type { WikiPage } from '@/types'
-
-const postOrderLabel: Record<FetchPostsOrder, string> = {
-    'title:asc': 'タイトル昇順',
-    'title:desc': 'タイトル降順',
-    'url:asc': 'URL 昇順',
-    'url:desc': 'URL 降順',
-    'original_created_at:asc': 'オリジナル投稿日時 昇順',
-    'original_created_at:desc': 'オリジナル投稿日時 降順',
-    'created_at:asc': '投稿日 昇順',
-    'created_at:desc': '投稿日 降順',
-    'updated_at:asc': '更新日 昇順',
-    'updated_at:desc': '更新日 降順',
-}
 
 const parseLimit = (value: string | null): 20 | 50 | 100 | null => {
   const n = Number (value)
   return n === 20 || n === 50 || n === 100 ? n : null
 }
 
-const parseOrder = (value: string | null): FetchPostsOrder | null =>
-    POST_LIST_ORDER_OPTIONS.some (option => option === value)
-    ? value as FetchPostsOrder
-    : null
-
 
 const PostListPage: FC = () => {
   const containerRef = useRef<HTMLDivElement | null> (null)
@@ -73,11 +50,7 @@ const PostListPage: FC = () => {
       ?? getClientListLimit ('postList')
       ?? DEFAULT_POST_LIST_LIMIT
   )
-  const order = (
+  const order = 'original_created_at:desc' as const
-      parseOrder (query.get ('order'))
-      ?? getClientListOrder<FetchPostsOrder> ('postList')
-      ?? DEFAULT_POST_LIST_ORDER
-  )
 
   const keys = {
       tags: tagsKey, match, page, limit,
@@ -92,14 +65,12 @@ const PostListPage: FC = () => {
   const totalPages = data ? Math.ceil (data.count / limit) : 0
 
   useEffect (() => {
-    setClientListSettings ('postList', { limit, order })
+    setClientListSettings ('postList', { limit })
-  }, [limit, order])
+  }, [limit])
 
-  const updateListQuery = (next: { limit?: 20 | 50 | 100
+  const updateListQuery = (next: { limit?: 20 | 50 | 100 }) => {
-				   order?: FetchPostsOrder }) => {
     const params = new URLSearchParams (location.search)
     params.set ('limit', String (next.limit ?? limit))
-    params.set ('order', next.order ?? order)
     params.set ('page', '1')
     navigate (`${ location.pathname }?${ params.toString () }`)
   }
@@ -146,39 +117,24 @@ const PostListPage: FC = () => {
 	}}/>
 
 	<MainArea>
-	  <div className="mb-4 flex flex-wrap gap-4 rounded-xl border border-border bg-background/80 p-4">
+	  <TabGroup
-	    <FormField label="表示件数">
+	      rightAddon={
-	      {() => (
+		  <label className="flex items-center gap-2 text-xs text-muted-foreground">
+		    <span>件数</span>
 		    <select
-		      className={inputClass (false)}
+			className="rounded border border-border bg-background px-2 py-1 text-sm
+				   text-foreground"
 			value={limit}
 			onChange={ev => updateListQuery ({
 			    limit: Number (ev.target.value) as 20 | 50 | 100,
 			})}>
 		      {LIST_LIMIT_OPTIONS.map (value => (
 			  <option key={value} value={value}>
-			  {value} 件
+			    {value}
 			  </option>))}
-		  </select>)}
+		    </select>
-	    </FormField>
+		  </label>
-
+	      }>
-	    <FormField label="並び順">
-	      {() => (
-		  <select
-		      className={inputClass (false)}
-		      value={order}
-		      onChange={ev => updateListQuery ({
-			  order: ev.target.value as FetchPostsOrder,
-		      })}>
-		    {POST_LIST_ORDER_OPTIONS.map (value => (
-			<option key={value} value={value}>
-			  {postOrderLabel[value]}
-			</option>))}
-		  </select>)}
-	    </FormField>
-	  </div>
-
-	  <TabGroup>
 	    <Tab name="広場">
 	      {posts.length > 0
 	       ? (

frontend/src/pages/posts/PostSearchPage.tsx

@@ -22,7 +22,6 @@ import {
     getClientListLimit,
     getClientListOrder,
     LIST_LIMIT_OPTIONS,
-    POST_LIST_ORDER_OPTIONS,
     setClientListSettings,
 } from '@/lib/settings'
 import { dateString, inputClass, originalCreatedAtString } from '@/lib/utils'
@@ -40,28 +39,30 @@ const setIf = (qs: URLSearchParams, k: string, v: string | null) => {
     qs.set (k, t)
 }
 
-const postOrderLabel: Record<FetchPostsOrder, string> = {
-    'title:asc': 'タイトル昇順',
-    'title:desc': 'タイトル降順',
-    'url:asc': 'URL 昇順',
-    'url:desc': 'URL 降順',
-    'original_created_at:asc': 'オリジナル投稿日時 昇順',
-    'original_created_at:desc': 'オリジナル投稿日時 降順',
-    'created_at:asc': '投稿日 昇順',
-    'created_at:desc': '投稿日 降順',
-    'updated_at:asc': '更新日 昇順',
-    'updated_at:desc': '更新日 降順',
-}
-
 const parseLimit = (value: string | null): 20 | 50 | 100 | null => {
   const n = Number (value)
   return n === 20 || n === 50 || n === 100 ? n : null
 }
 
-const parseOrder = (value: string | null): FetchPostsOrder | null =>
+const parseOrder = (value: string | null): FetchPostsOrder | null => {
-    POST_LIST_ORDER_OPTIONS.some (option => option === value)
+  switch (value)
-    ? value as FetchPostsOrder
+  {
-    : null
+  case 'title:asc':
+  case 'title:desc':
+  case 'url:asc':
+  case 'url:desc':
+  case 'original_created_at:asc':
+  case 'original_created_at:desc':
+  case 'created_at:asc':
+  case 'created_at:desc':
+  case 'updated_at:asc':
+  case 'updated_at:desc':
+    return value
+
+  default:
+    return null
+  }
+}
 
 
 const PostSearchPage: FC = () => {
@@ -188,41 +189,26 @@ const PostSearchPage: FC = () => {
 	</Helmet>
 
 	<div className="max-w-xl">
+	  <div className="flex flex-wrap items-center justify-between gap-3">
 	    <PageTitle>広場検索</PageTitle>
-
+	    <label className="flex items-center gap-2 text-xs text-muted-foreground">
-	  <form onSubmit={handleSearch} className="space-y-2">
+	      <span>件数</span>
-	    <div className="grid gap-3 rounded-xl border border-border bg-background/80 p-3 sm:grid-cols-2">
-	      <FormField label="表示件数">
-		{() => (
 	      <select
-			className={inputClass (false)}
+		  className="rounded border border-border bg-background px-2 py-1 text-sm
+			     text-foreground"
 		  value={limit}
 		  onChange={ev => updateListQuery ({
 		      limit: Number (ev.target.value) as 20 | 50 | 100,
 		  })}>
 		{LIST_LIMIT_OPTIONS.map (value => (
 		    <option key={value} value={value}>
-			    {value} 件
+		      {value}
 		    </option>))}
-		    </select>)}
+	      </select>
-	      </FormField>
+	    </label>
-
-	      <FormField label="並び順">
-		{() => (
-		    <select
-			className={inputClass (false)}
-			value={order}
-			onChange={ev => updateListQuery ({
-			    order: ev.target.value as FetchPostsOrder,
-			})}>
-		      {POST_LIST_ORDER_OPTIONS.map (value => (
-			  <option key={value} value={value}>
-			    {postOrderLabel[value]}
-			  </option>))}
-		    </select>)}
-	      </FormField>
 	  </div>
 
+	  <form onSubmit={handleSearch} className="space-y-2">
 	    {/* タイトル */}
 	    <FormField label="タイトル">
 	      {({ invalid }) => (

frontend/src/pages/tags/TagListPage.tsx

@@ -21,7 +21,6 @@ import {
     getClientListOrder,
     LIST_LIMIT_OPTIONS,
     setClientListSettings,
-    TAG_LIST_ORDER_OPTIONS,
 } from '@/lib/settings'
 import { fetchTags } from '@/lib/tags'
 import { dateString, inputClass } from '@/lib/utils'
@@ -44,28 +43,30 @@ const boolFromQuery = (value: string | null): boolean =>
 
 const tagStateLabel = (deprecatedAt: string | null) => deprecatedAt ? '廃止' : ''
 
-const tagOrderLabel: Record<FetchTagsOrder, string> = {
-    'name:asc': '名前昇順',
-    'name:desc': '名前降順',
-    'category:asc': 'カテゴリ昇順',
-    'category:desc': 'カテゴリ降順',
-    'post_count:asc': '件数昇順',
-    'post_count:desc': '件数降順',
-    'created_at:asc': '最初の記載日時 昇順',
-    'created_at:desc': '最初の記載日時 降順',
-    'updated_at:asc': '更新日時 昇順',
-    'updated_at:desc': '更新日時 降順',
-}
-
 const parseLimit = (value: string | null): 20 | 50 | 100 | null => {
   const n = Number (value)
   return n === 20 || n === 50 || n === 100 ? n : null
 }
 
-const parseOrder = (value: string | null): FetchTagsOrder | null =>
+const parseOrder = (value: string | null): FetchTagsOrder | null => {
-    TAG_LIST_ORDER_OPTIONS.some (option => option === value)
+  switch (value)
-    ? value as FetchTagsOrder
+  {
-    : null
+  case 'name:asc':
+  case 'name:desc':
+  case 'category:asc':
+  case 'category:desc':
+  case 'post_count:asc':
+  case 'post_count:desc':
+  case 'created_at:asc':
+  case 'created_at:desc':
+  case 'updated_at:asc':
+  case 'updated_at:desc':
+    return value
+
+  default:
+    return null
+  }
+}
 
 
 const TagListPage: FC = () => {
@@ -192,41 +193,26 @@ const TagListPage: FC = () => {
 	</Helmet>
 
 	<div className="max-w-xl">
+	  <div className="flex flex-wrap items-center justify-between gap-3">
 	    <PageTitle>タグ</PageTitle>
-
+	    <label className="flex items-center gap-2 text-xs text-muted-foreground">
-	  <form onSubmit={handleSearch} className="space-y-2">
+	      <span>件数</span>
-	    <div className="grid gap-3 rounded-xl border border-border bg-background/80 p-3 sm:grid-cols-2">
-	      <FormField label="表示件数">
-		{() => (
 	      <select
 		  value={limit}
 		  onChange={ev => updateListQuery ({
 		      limit: Number (ev.target.value) as 20 | 50 | 100,
 		  })}
-			className={inputClass (false)}>
+		  className="rounded border border-border bg-background px-2 py-1 text-sm
+			     text-foreground">
 		{LIST_LIMIT_OPTIONS.map (value => (
 		    <option key={value} value={value}>
-			    {value} 件
+		      {value}
 		    </option>))}
-		    </select>)}
+	      </select>
-	      </FormField>
+	    </label>
-
-	      <FormField label="並び順">
-		{() => (
-		    <select
-			value={order}
-			onChange={ev => updateListQuery ({
-			    order: ev.target.value as FetchTagsOrder,
-			})}
-			className={inputClass (false)}>
-		      {TAG_LIST_ORDER_OPTIONS.map (value => (
-			  <option key={value} value={value}>
-			    {tagOrderLabel[value]}
-			  </option>))}
-		    </select>)}
-	      </FormField>
 	  </div>
 
+	  <form onSubmit={handleSearch} className="space-y-2">
 	    {/* 名前 */}
 	    <FormField label="名前">
 	      {({ invalid }) => (

frontend/src/pages/users/SettingPage.tsx

@@ -1,11 +1,6 @@
-import type {
+import type { CSSProperties, Dispatch, FC, KeyboardEvent, SetStateAction } from 'react'
-    Dispatch,
-    FC,
-    KeyboardEvent,
-    SetStateAction,
-} from 'react'
 
-import { useCallback, useEffect, useMemo, useState } from 'react'
+import { useEffect, useMemo, useState } from 'react'
 import { Helmet } from 'react-helmet-async'
 import { useLocation, useNavigate } from 'react-router-dom'
 
@@ -14,92 +9,84 @@ import FormField from '@/components/common/FormField'
 import Label from '@/components/common/Label'
 import PageTitle from '@/components/common/PageTitle'
 import MainArea from '@/components/layout/MainArea'
-import { useUserSettings } from '@/components/users/UserSettingsProvider'
+import TagLink from '@/components/TagLink'
 import InheritDialogue from '@/components/users/InheritDialogue'
 import UserCodeDialogue from '@/components/users/UserCodeDialogue'
+import { CATEGORY_NAMES, CATEGORIES } from '@/consts'
 import { Button } from '@/components/ui/button'
 import { toast } from '@/components/ui/use-toast'
 import { SITE_TITLE } from '@/config'
 import { apiPut } from '@/lib/api'
 import {
-    AUTO_FETCH_OPTIONS,
+    applyThemeSelection,
+    BUILTIN_THEMES,
+    createCustomThemeFromBase,
+    defaultThemeTagColoursFor,
     DEFAULT_USER_SETTINGS,
-    THEME_OPTIONS,
+    deriveUserThemeModeFromSelection,
-    WIKI_EDITOR_MODE_OPTIONS,
+    fetchUserSettings,
+    hasStoredClientThemeSelection,
+    getClientActiveThemeId,
+    getClientCustomThemes,
+    getResolvedThemeFromSelection,
+    setClientAppearanceThemes,
     updateUserSettings,
 } from '@/lib/settings'
 import { cn, inputClass } from '@/lib/utils'
 import { useValidationErrors } from '@/lib/useValidationErrors'
 
-import type { User } from '@/types'
+import type { Category, Tag, User } from '@/types'
-import type { UserSettings } from '@/lib/settings'
+import type {
+    ActiveThemeId,
+    ClientTheme,
+    CustomClientTheme,
+    ThemeTagColours,
+    UserSettings,
+} from '@/lib/settings'
 
-type Props = { user:    User | null
+type Props = {
-	       setUser: Dispatch<SetStateAction<User | null>> }
+    user:     User | null
+    setUser:  Dispatch<SetStateAction<User | null>>
+}
 
 type UserFormField = 'name'
-type SettingsFormField =
+type SettingsFormField = 'theme'
-    | 'theme'
+type SettingsTab = 'account' | 'theme' | 'keyboard'
-    | 'autoFetchTitle'
-    | 'autoFetchThumbnail'
-    | 'wikiEditorMode'
-
-type SettingsTab = 'account' | 'theme' | 'keyboard' | 'editing' | 'wiki'
 
 type TabSpec = {
     id:     SettingsTab
     label:  string }
 
-type NameFieldErrors = Partial<Record<UserFormField, string[]>>
-type SettingsFieldErrors = Partial<Record<SettingsFormField, string[]>>
-
 type SharedSectionProps = {
-    draftSettings:         UserSettings
+    user:                  User
     name:                  string
-    nameBaseErrors:        string[]
-    nameFieldErrors:       NameFieldErrors
-    onDraftSettingsChange: Dispatch<SetStateAction<UserSettings>>
-    onInheritOpen:         () => void
     onNameChange:          (value: string) => void
-    onSettingsSubmit:      () => void
+    onInheritOpen:         () => void
     onUserCodeOpen:        () => void
     onUserSubmit:          () => void
+    userBaseErrors:        string[]
+    userFieldErrors:       Partial<Record<UserFormField, string[]>>
+    draftActiveThemeId:    ActiveThemeId
+    draftCustomThemes:     Record<string, CustomClientTheme>
+    selectedTheme:         ClientTheme
+    draftTagColours:       ThemeTagColours
+    onThemeChange:         (themeId: ActiveThemeId) => void
+    onTagColourChange:     (category: Category, colour: string) => void
+    onResetAllTagColours:  () => void
+    onResetTagColour:      (category: Category) => void
+    onThemeSubmit:         () => void
     settingsBaseErrors:    string[]
-    settingsFieldErrors:   SettingsFieldErrors
+    settingsFieldErrors:   Partial<Record<SettingsFormField, string[]>>
-    user:                  User }
+}
-
-const sectionClassName =
-    'space-y-4 rounded-xl border border-border bg-background/80 p-4'
-
-const desktopTabRailClassName = [
-    'hidden md:flex md:justify-center',
-].join (' ')
-
-const desktopTabRailInnerClassName = [
-    'grid w-fit grid-cols-[12rem_minmax(0,36rem)] items-start gap-6',
-].join (' ')
 
 const tabs: TabSpec[] = [
     { id: 'account', label: 'アカウント' },
     { id: 'theme', label: 'テーマ' },
     { id: 'keyboard', label: 'キーボード' },
-    { id: 'editing', label: '編輯支援' },
-    { id: 'wiki', label: 'Wiki' },
 ]
 
-const settingsTabByField: Record<SettingsFormField, SettingsTab> = {
+const sectionClassName =
-    theme:               'theme',
+    'space-y-4 rounded-xl border border-border bg-background/80 p-4'
-    autoFetchTitle:      'editing',
-    autoFetchThumbnail:  'editing',
-    wikiEditorMode:      'wiki',
-}
-
-const settingsFieldOrder: SettingsFormField[] = [
-    'theme',
-    'autoFetchTitle',
-    'autoFetchThumbnail',
-    'wikiEditorMode',
-]
 
 const themeLabel: Record<UserSettings['theme'], string> = {
     system: 'システム設定に従う',
@@ -107,40 +94,64 @@ const themeLabel: Record<UserSettings['theme'], string> = {
     dark:   'ダーク・モード',
 }
 
-const autoFetchLabel: Record<UserSettings['autoFetchTitle'], string> = {
+const builtinThemeLabel: Record<'light' | 'dark', string> = {
-    auto:   '自動',
+    light: 'ライト・モード',
-    manual: '手動',
+    dark:  'ダーク・モード',
-    off:    '無効',
-}
-
-const wikiEditorModeLabel: Record<UserSettings['wikiEditorMode'], string> = {
-    split:   '左右表示',
-    write:   '本文のみ',
-    preview: 'プレビューのみ',
 }
 
 const keyboardShortcutRows = [
-    { action: '投稿詳細を開く', key: 'Enter', scope: '一覧・検索結果', conflict: 'なし' },
+    {
-    { action: '候補タグを選ぶ', key: '↑ / ↓ / Enter', scope: 'タグ入力', conflict: 'なし' },
+	action:   '投稿詳細を開く',
-    { action: '候補タグを閉ぢる', key: 'Escape', scope: 'タグ入力', conflict: 'なし' },
+	key:      'Enter',
+	scope:    '一覧・検索結果',
+	conflict: 'なし',
+    },
+    {
+	action:   '候補タグを選ぶ',
+	key:      '↑ / ↓ / Enter',
+	scope:    'タグ入力',
+	conflict: 'なし',
+    },
+    {
+	action:   '候補タグを閉じる',
+	key:      'Escape',
+	scope:    'タグ入力',
+	conflict: 'なし',
+    },
 ]
 
-const themeColorTargets = [
+const previewTag = (
-    '背景色',
+    id:         number,
-    '文字色',
+    name:       string,
-    '枠線色',
+    category:   Category,
-    'リンク色',
+    postCount:  number,
-    '強調色',
+    hasWiki:    boolean,
-    '通常タグ',
+    options?:   { hasDeerjikists?: boolean },
-    'キャラタグ',
+): Tag => ({
-    '素材タグ',
+    id,
-    'Nico タグ',
+    name,
-    '廃止タグ',
+    category,
-    'Wiki ありタグ',
+    deprecatedAt: null,
-    'Wiki 未作成タグ',
+    aliases: [],
-    '選択中タグ',
+    parents: [],
-    'ホバー中タグ',
+    postCount,
-]
+    createdAt: '',
+    updatedAt: '',
+    hasWiki,
+    materialId: null,
+    hasDeerjikists: options?.hasDeerjikists ?? false,
+    children: [],
+})
+
+const previewTags: Record<Category, Tag> = {
+    deerjikist: previewTag (1, 'にじらー', 'deerjikist', 12, true, { hasDeerjikists: true }),
+    meme: previewTag (2, 'ミーム', 'meme', 34, true),
+    character: previewTag (3, 'キャラクター', 'character', 56, false),
+    general: previewTag (4, '一般', 'general', 78, true),
+    material: previewTag (5, '素材', 'material', 90, false),
+    meta: previewTag (6, 'メタ', 'meta', 21, true),
+    nico: previewTag (7, 'nico:sm9', 'nico', 43, false),
+}
 
 
 const parseTab = (search: string): SettingsTab => {
@@ -155,21 +166,42 @@ const tabButtonId = (tab: SettingsTab): string => `settings-tab-${ tab }`
 const tabPanelId = (tab: SettingsTab): string => `settings-panel-${ tab }`
 
 
+const themePreviewStyle = (tagColours: ThemeTagColours): CSSProperties =>
+    Object.fromEntries (
+	CATEGORIES.flatMap (category => [
+	    [`--tag-colour-${ category }`, tagColours[category]],
+	    [`--tag-colour-${ category }-hover`, tagColours[category]],
+	]),
+    ) as CSSProperties
+
+
+const themeLabelById = (
+    themeId:       ActiveThemeId,
+    customThemes:  Record<string, CustomClientTheme>,
+): string => {
+  if (themeId === 'system')
+    return themeLabel.system
+  if (themeId === 'light' || themeId === 'dark')
+    return builtinThemeLabel[themeId]
+  return (customThemes[themeId] ?? BUILTIN_THEMES.light).name
+}
+
+
 const AccountSection: FC<SharedSectionProps> = ({
     name,
-    nameBaseErrors,
-    nameFieldErrors,
     onInheritOpen,
     onNameChange,
     onUserCodeOpen,
     onUserSubmit,
     user,
+    userBaseErrors,
+    userFieldErrors,
 }) => (
     <section className={sectionClassName}>
       <h2 className="text-xl font-bold">アカウント</h2>
-      <FieldError messages={nameBaseErrors}/>
+      <FieldError messages={userBaseErrors}/>
 
-      <FormField label="表示名" messages={nameFieldErrors.name}>
+      <FormField label="表示名" messages={userFieldErrors.name}>
 	{({ describedBy, invalid }) => (
 	    <>
 	      <input
@@ -216,9 +248,15 @@ const AccountSection: FC<SharedSectionProps> = ({
 
 
 const ThemeSection: FC<SharedSectionProps> = ({
-    draftSettings,
+    draftActiveThemeId,
-    onDraftSettingsChange,
+    draftCustomThemes,
-    onSettingsSubmit,
+    selectedTheme,
+    draftTagColours,
+    onResetAllTagColours,
+    onResetTagColour,
+    onTagColourChange,
+    onThemeChange,
+    onThemeSubmit,
     settingsBaseErrors,
     settingsFieldErrors,
 }) => (
@@ -230,37 +268,119 @@ const ThemeSection: FC<SharedSectionProps> = ({
 	{() => (
 	    <select
 		className={inputClass (Boolean (settingsFieldErrors.theme?.length))}
-		value={draftSettings.theme}
+		value={draftActiveThemeId}
-		onChange={ev => onDraftSettingsChange (current => ({
+		onChange={ev => onThemeChange (ev.target.value as ActiveThemeId)}>
-		    ...current,
+	      <option value="system">{themeLabel.system}</option>
-		    theme: ev.target.value as UserSettings['theme'],
+	      <option value="light">{builtinThemeLabel.light}</option>
-		}))}>
+	      <option value="dark">{builtinThemeLabel.dark}</option>
-	      {THEME_OPTIONS.map (value => (
+	      {Object.values (draftCustomThemes).length > 0 && (
-		  <option key={value} value={value}>
+		  <optgroup label="カスタムテーマ">
-		    {themeLabel[value]}
+		    {Object.values (draftCustomThemes).map (theme => (
+			<option key={theme.id} value={theme.id}>
+			  {theme.name}
 			</option>))}
+		  </optgroup>)}
 	    </select>)}
       </FormField>
 
-      <div className="space-y-2 rounded-lg border border-border/70 bg-muted/30 p-3 text-sm">
+      <div className="space-y-2 rounded-lg border border-dashed border-border/70 p-3 text-sm">
-	<p className="font-medium">今後の拡張予定</p>
 	<p>
-	  将来は `themes` または `user_themes` を導入し，ユーザごとの
+	  テーマの選択状態は現在のブラウザに保存し，背景・文字色はそのテーマの base に従います．
-	  カスタム・テーマを持てる構造にする前提です．
 	</p>
-	<p>その際は次の色を個別に設定できるようにします．</p>
+	<p className="text-muted-foreground">
-	<div className="flex flex-wrap gap-2">
+	  backend には system / light / dark の mode だけ保存します．
-	  {themeColorTargets.map (target => (
+	  カスタムテーマ本体は今は browser-local です．
-	      <span
+	</p>
-		  key={target}
+	<p className="text-muted-foreground">
-		  className="rounded-full border border-border/70 px-2 py-1">
+	  将来は themes テーブルなどへ移して，端末間同期できる構造に拡張できます．
-		{target}
+	</p>
-	      </span>))}
+      </div>
+
+      <div className="space-y-3">
+	<div className="flex flex-wrap items-center justify-between gap-2">
+	  <div>
+	  <h3 className="font-medium">タグカテゴリ色</h3>
+	  <p className="text-sm text-muted-foreground">
+	    {selectedTheme.builtin || draftActiveThemeId === 'system'
+	     ? '組み込みテーマは直接変更されません．色を変更するとカスタムテーマを作成します．'
+	     : `現在の編輯対象: ${ selectedTheme.name }`}
+	  </p>
+	  </div>
+	  <Button
+	      type="button"
+	      variant="outline"
+	      onClick={onResetAllTagColours}
+	      disabled={selectedTheme.builtin || draftActiveThemeId === 'system'}>
+	    すべてのタグ色を既定に戻す
+	  </Button>
+	</div>
+
+	<div className="grid gap-3 sm:grid-cols-2">
+	  {CATEGORIES.map (category => {
+	      const resolvedDefaults =
+		  defaultThemeTagColoursFor (selectedTheme.baseTheme)
+	      const isDefault =
+		  draftTagColours[category] === resolvedDefaults[category]
+
+	      return (
+		  <div
+		      key={category}
+		      className="space-y-2 rounded-lg border border-border/70 px-3 py-2">
+		    <div className="flex items-center justify-between gap-3">
+		      <span className="text-sm">{CATEGORY_NAMES[category]}</span>
+		      <input
+			  type="color"
+			  value={draftTagColours[category]}
+			  onChange={ev => onTagColourChange (category, ev.target.value)}
+			  className="h-10 w-16 cursor-pointer rounded border border-border
+				     bg-transparent p-1"/>
+		    </div>
+		    <div className="flex justify-end">
+		      <Button
+			  type="button"
+			  variant="ghost"
+			  className="h-auto px-0 py-0 text-xs"
+			  onClick={() => onResetTagColour (category)}
+			  disabled={
+			      isDefault
+			      || selectedTheme.builtin
+			      || draftActiveThemeId === 'system'
+			  }>
+			既定に戻す
+		      </Button>
+		    </div>
+		  </div>)
+	  })}
 	</div>
       </div>
 
-      <Button type="button" onClick={onSettingsSubmit}>
+      <div className="space-y-2 rounded-lg border border-border bg-background p-3
-	設定を保存
+		      text-foreground shadow-sm transition-colors">
+	<p className="text-sm font-medium">プレビュー</p>
+	<p className="text-xs text-muted-foreground">
+	  現在の表示テーマ: {themeLabelById (draftActiveThemeId, draftCustomThemes)}
+	</p>
+	<div className="flex flex-wrap gap-3" style={themePreviewStyle (draftTagColours)}>
+	  {CATEGORIES.map (category => (
+	      <TagLink
+		  key={category}
+		  tag={previewTags[category]}
+		  linkFlg={false}
+		  truncateOnMobile
+		  withWiki={false}/>))}
+	</div>
+      </div>
+
+      <div className="space-y-2 rounded-lg border border-dashed border-border/70 p-3 text-sm">
+	<p className="font-medium">既存 backend 設定について</p>
+	<p>
+	  auto_fetch_title、auto_fetch_thumbnail、wiki_editor_mode は backend 側に
+	  保持したままです．この共通設定画面にはまだ接続していません．
+	</p>
+      </div>
+
+      <Button type="button" onClick={onThemeSubmit}>
+	テーマを保存
       </Button>
     </section>)
 
@@ -269,13 +389,10 @@ const KeyboardSection: FC = () => (
     <section className={sectionClassName}>
       <h2 className="text-xl font-bold">キーボード</h2>
 
-      <div className="space-y-2 rounded-lg border border-border/70 bg-muted/30 p-3 text-sm">
+      <p className="text-sm text-muted-foreground">
-	<p>
+	現段階では一覧表示のみです．将来は action / key / scope / conflict を持つ
-	  初期実装では固定ショートカット一覧のみを表示します．
+	key bind 設定へ拡張できる形にしています．
-	  将来は `action / key / scope / conflict` を持つ
-	  key bind 設定へ拡張する前提です．
       </p>
-      </div>
 
       <div className="overflow-x-auto">
 	<table className="w-full min-w-[28rem] table-fixed border-collapse text-sm">
@@ -301,111 +418,29 @@ const KeyboardSection: FC = () => (
     </section>)
 
 
-const EditingSection: FC<SharedSectionProps> = ({
-    draftSettings,
-    onDraftSettingsChange,
-    onSettingsSubmit,
-    settingsBaseErrors,
-    settingsFieldErrors,
-}) => (
-    <section className={sectionClassName}>
-      <h2 className="text-xl font-bold">編輯支援</h2>
-      <FieldError messages={settingsBaseErrors}/>
-
-      <FormField label="タイトル自動取得" messages={settingsFieldErrors.autoFetchTitle}>
-	{() => (
-	    <select
-		className={inputClass (
-		    Boolean (settingsFieldErrors.autoFetchTitle?.length),
-		)}
-		value={draftSettings.autoFetchTitle}
-		onChange={ev => onDraftSettingsChange (current => ({
-		    ...current,
-		    autoFetchTitle: ev.target.value as UserSettings['autoFetchTitle'],
-		}))}>
-	      {AUTO_FETCH_OPTIONS.map (value => (
-		  <option key={value} value={value}>
-		    {autoFetchLabel[value]}
-		  </option>))}
-	    </select>)}
-      </FormField>
-
-      <FormField
-	  label="サムネール自動取得"
-	  messages={settingsFieldErrors.autoFetchThumbnail}>
-	{() => (
-	    <select
-		className={inputClass (
-		    Boolean (settingsFieldErrors.autoFetchThumbnail?.length),
-		)}
-		value={draftSettings.autoFetchThumbnail}
-		onChange={ev => onDraftSettingsChange (current => ({
-		    ...current,
-		    autoFetchThumbnail:
-			ev.target.value as UserSettings['autoFetchThumbnail'],
-		}))}>
-	      {AUTO_FETCH_OPTIONS.map (value => (
-		  <option key={value} value={value}>
-		    {autoFetchLabel[value]}
-		  </option>))}
-	    </select>)}
-      </FormField>
-
-      <Button type="button" onClick={onSettingsSubmit}>
-	設定を保存
-      </Button>
-    </section>)
-
-
-const WikiSection: FC<SharedSectionProps> = ({
-    draftSettings,
-    onDraftSettingsChange,
-    onSettingsSubmit,
-    settingsBaseErrors,
-    settingsFieldErrors,
-}) => (
-    <section className={sectionClassName}>
-      <h2 className="text-xl font-bold">Wiki</h2>
-      <FieldError messages={settingsBaseErrors}/>
-
-      <FormField label="エディタ表示" messages={settingsFieldErrors.wikiEditorMode}>
-	{() => (
-	    <select
-		className={inputClass (
-		    Boolean (settingsFieldErrors.wikiEditorMode?.length),
-		)}
-		value={draftSettings.wikiEditorMode}
-		onChange={ev => onDraftSettingsChange (current => ({
-		    ...current,
-		    wikiEditorMode: ev.target.value as UserSettings['wikiEditorMode'],
-		}))}>
-	      {WIKI_EDITOR_MODE_OPTIONS.map (value => (
-		  <option key={value} value={value}>
-		    {wikiEditorModeLabel[value]}
-		  </option>))}
-	    </select>)}
-      </FormField>
-
-      <Button type="button" onClick={onSettingsSubmit}>
-	設定を保存
-      </Button>
-    </section>)
-
-
 const SettingPage: FC<Props> = ({ user, setUser }) => {
   const location = useLocation ()
   const navigate = useNavigate ()
 
-  const [draftSettings, setDraftSettings] = useState<UserSettings> (DEFAULT_USER_SETTINGS)
-  const [name, setName] = useState ('')
-  const [userCodeVsbl, setUserCodeVsbl] = useState (false)
   const [inheritVsbl, setInheritVsbl] = useState (false)
-  const { error, loaded, settings, setSettings } = useUserSettings ()
+  const [loading, setLoading] = useState (true)
+  const [name, setName] = useState ('')
+  const [settingsError, setSettingsError] = useState<string | null> (null)
+  const [, setDraftSettings] = useState<UserSettings> (DEFAULT_USER_SETTINGS)
+  const [savedActiveThemeId, setSavedActiveThemeId] =
+      useState<ActiveThemeId> (getClientActiveThemeId ())
+  const [savedCustomThemes, setSavedCustomThemes] =
+      useState<Record<string, CustomClientTheme>> (getClientCustomThemes ())
+  const [draftActiveThemeId, setDraftActiveThemeId] =
+      useState<ActiveThemeId> (getClientActiveThemeId ())
+  const [draftCustomThemes, setDraftCustomThemes] =
+      useState<Record<string, CustomClientTheme>> (getClientCustomThemes ())
+  const [userCodeVsbl, setUserCodeVsbl] = useState (false)
   const {
-    baseErrors: nameBaseErrors,
+    baseErrors: userBaseErrors,
-    fieldErrors: nameFieldErrors,
+    fieldErrors: userFieldErrors,
-    clearValidationErrors: clearNameValidationErrors,
+    clearValidationErrors: clearUserValidationErrors,
-    applyValidationError: applyNameValidationError,
+    applyValidationError: applyUserValidationError,
   } = useValidationErrors<UserFormField> ()
   const {
     baseErrors: settingsBaseErrors,
@@ -415,40 +450,80 @@ const SettingPage: FC<Props> = ({ user, setUser }) => {
   } = useValidationErrors<SettingsFormField> ()
 
   const activeTab = useMemo<SettingsTab> (() => parseTab (location.search), [location.search])
+  const selectedTheme = useMemo<ClientTheme> (
+      () => getResolvedThemeFromSelection (draftActiveThemeId, draftCustomThemes),
+      [draftActiveThemeId, draftCustomThemes],
+  )
+  const draftTagColours = selectedTheme.tagColours
 
-  const setActiveTab = useCallback ((tab: SettingsTab) => {
+  const setActiveTab = (tab: SettingsTab) => {
     const params = new URLSearchParams (location.search)
     params.set ('tab', tab)
     navigate (
-	`${ location.pathname }${ params.toString () ? `?${ params.toString () }` : '' }`,
+	`${ location.pathname }?${ params.toString () }`,
 	{ replace: true },
     )
-  }, [location.pathname, location.search, navigate])
+  }
 
   const settingsTabErrors = useMemo<Record<SettingsTab, boolean>> (() => ({
-      account: Boolean (nameFieldErrors.name?.length),
+      account: Boolean (userFieldErrors.name?.length),
       theme: Boolean (settingsFieldErrors.theme?.length),
       keyboard: false,
-      editing: (
+  }), [settingsFieldErrors.theme, userFieldErrors.name])
-	  Boolean (settingsFieldErrors.autoFetchTitle?.length)
+
-	  || Boolean (settingsFieldErrors.autoFetchThumbnail?.length)
+  const applyDraftThemeSelection = (
-      ),
+      activeThemeId: ActiveThemeId,
-      wiki: Boolean (settingsFieldErrors.wikiEditorMode?.length),
+      customThemes:  Record<string, CustomClientTheme>,
-  }), [nameFieldErrors.name, settingsFieldErrors])
+  ) => {
+    setDraftActiveThemeId (activeThemeId)
+    setDraftCustomThemes (customThemes)
+    setDraftSettings (current => ({
+	...current,
+	theme: deriveUserThemeModeFromSelection (activeThemeId, customThemes),
+    }))
+    applyThemeSelection (activeThemeId, customThemes)
+  }
+
+  const ensureEditableCustomTheme = (): {
+      activeThemeId: ActiveThemeId
+      customThemes:  Record<string, CustomClientTheme>
+  } => {
+    if (draftActiveThemeId !== 'system' && draftCustomThemes[draftActiveThemeId] != null)
+      {
+	return {
+	    activeThemeId: draftActiveThemeId,
+	    customThemes: draftCustomThemes,
+	}
+      }
+
+    const customTheme = createCustomThemeFromBase (
+	selectedTheme.baseTheme,
+	{ ...selectedTheme.tagColours },
+    )
+    const nextCustomThemes = {
+	...draftCustomThemes,
+	[customTheme.id]: customTheme,
+    }
+
+    return {
+	activeThemeId: customTheme.id,
+	customThemes: nextCustomThemes,
+    }
+  }
 
   const handleTabKeyDown = (event: KeyboardEvent<HTMLButtonElement>) => {
     const currentIndex = tabs.findIndex (tab => tab.id === activeTab)
 
     switch (event.key)
     {
-    case 'ArrowRight':
     case 'ArrowDown':
+    case 'ArrowRight':
       event.preventDefault ()
       setActiveTab (tabs[(currentIndex + 1) % tabs.length].id)
       break
 
-    case 'ArrowLeft':
     case 'ArrowUp':
+    case 'ArrowLeft':
       event.preventDefault ()
       setActiveTab (tabs[(currentIndex - 1 + tabs.length) % tabs.length].id)
       break
@@ -469,7 +544,7 @@ const SettingPage: FC<Props> = ({ user, setUser }) => {
     if (!(user))
       return
 
-    clearNameValidationErrors ()
+    clearUserValidationErrors ()
 
     const formData = new FormData
     formData.append ('name', name)
@@ -484,30 +559,30 @@ const SettingPage: FC<Props> = ({ user, setUser }) => {
     }
     catch (submitError)
     {
-      applyNameValidationError (submitError)
+      applyUserValidationError (submitError)
       toast ({ title: '表示名を更新できませんでした．' })
     }
   }
 
-  const handleSettingsSubmit = async () => {
+  const handleThemeSubmit = async () => {
     clearSettingsValidationErrors ()
 
     try
     {
-      const data = await updateUserSettings ({
+      const themeMode =
-	  theme: draftSettings.theme,
+	  deriveUserThemeModeFromSelection (draftActiveThemeId, draftCustomThemes)
-	  auto_fetch_title: draftSettings.autoFetchTitle,
+      const data = await updateUserSettings ({ theme: themeMode })
-	  auto_fetch_thumbnail: draftSettings.autoFetchThumbnail,
+      setDraftSettings ({ ...data, theme: themeMode })
-	  wiki_editor_mode: draftSettings.wikiEditorMode,
+      setSavedActiveThemeId (draftActiveThemeId)
-      })
+      setSavedCustomThemes (draftCustomThemes)
-      setDraftSettings (data)
+      setClientAppearanceThemes (draftActiveThemeId, draftCustomThemes)
-      setSettings (data)
+      applyThemeSelection (draftActiveThemeId, draftCustomThemes)
-      toast ({ title: '設定を保存しました．' })
+      toast ({ title: 'テーマ設定を保存しました．' })
     }
     catch (submitError)
     {
       applySettingsValidationError (submitError)
-      toast ({ title: '設定を保存できませんでした．' })
+      toast ({ title: 'テーマ設定を保存できませんでした．' })
     }
   }
 
@@ -519,36 +594,140 @@ const SettingPage: FC<Props> = ({ user, setUser }) => {
   }, [user])
 
   useEffect (() => {
-    setDraftSettings (settings)
+    if (!(user))
-  }, [settings])
+      return
+
+    let cancelled = false
+
+    void (async () => {
+      setLoading (true)
+
+      try
+      {
+	const data = await fetchUserSettings ()
+	if (cancelled)
+	  return
+
+	const customThemes = getClientCustomThemes ()
+	const activeThemeId = hasStoredClientThemeSelection ()
+	    ? getClientActiveThemeId ()
+	    : data.theme
+	const themeMode = deriveUserThemeModeFromSelection (activeThemeId, customThemes)
+
+	setDraftSettings ({ ...data, theme: themeMode })
+	setSavedActiveThemeId (activeThemeId)
+	setSavedCustomThemes (customThemes)
+	setDraftActiveThemeId (activeThemeId)
+	setDraftCustomThemes (customThemes)
+	setSettingsError (null)
+      }
+      catch
+      {
+	if (cancelled)
+	  return
+
+	setSettingsError ('設定の読込みに失敗しました．')
+      }
+      finally
+      {
+	if (!(cancelled))
+	  setLoading (false)
+      }
+    }) ()
+
+    return () => {
+      cancelled = true
+    }
+  }, [user])
 
   useEffect (() => {
-    if (nameFieldErrors.name?.length)
+    if (userFieldErrors.name?.length)
       setActiveTab ('account')
-  }, [nameFieldErrors.name, setActiveTab])
+  }, [location.pathname, location.search, userFieldErrors.name])
 
   useEffect (() => {
-    const fieldWithError = settingsFieldOrder.find (
+    if (settingsFieldErrors.theme?.length)
-	field => (settingsFieldErrors[field]?.length ?? 0) > 0,
+      setActiveTab ('theme')
-    )
+  }, [location.pathname, location.search, settingsFieldErrors.theme])
-    if (fieldWithError)
+
-      setActiveTab (settingsTabByField[fieldWithError])
+  useEffect (() => {
-  }, [setActiveTab, settingsFieldErrors])
+    applyThemeSelection (draftActiveThemeId, draftCustomThemes)
+
+    return () => {
+      applyThemeSelection (savedActiveThemeId, savedCustomThemes)
+    }
+  }, [draftActiveThemeId, draftCustomThemes, savedActiveThemeId, savedCustomThemes])
 
   const sectionProps: SharedSectionProps | null = user ? {
-      draftSettings,
+      user,
       name,
-      nameBaseErrors,
-      nameFieldErrors,
-      onDraftSettingsChange: setDraftSettings,
-      onInheritOpen: () => setInheritVsbl (true),
       onNameChange: setName,
-      onSettingsSubmit: handleSettingsSubmit,
+      onInheritOpen: () => setInheritVsbl (true),
       onUserCodeOpen: () => setUserCodeVsbl (true),
       onUserSubmit: handleUserSubmit,
+      userBaseErrors,
+      userFieldErrors,
+      draftActiveThemeId,
+      draftCustomThemes,
+      selectedTheme,
+      draftTagColours,
+      onThemeChange: themeId => {
+	  applyDraftThemeSelection (themeId, draftCustomThemes)
+      },
+      onTagColourChange: (category, colour) => {
+	  const editable = ensureEditableCustomTheme ()
+	  const editableTheme = editable.customThemes[editable.activeThemeId]
+	  const nextCustomThemes = {
+	      ...editable.customThemes,
+	      [editable.activeThemeId]: {
+		  ...editableTheme,
+		  tagColours: {
+		      ...editableTheme.tagColours,
+		      [category]: colour,
+		  },
+	      },
+	  }
+	  applyDraftThemeSelection (editable.activeThemeId, nextCustomThemes)
+      },
+      onResetAllTagColours: () => {
+	  if (selectedTheme.builtin || draftActiveThemeId === 'system')
+	    return
+
+	  applyDraftThemeSelection (
+	      draftActiveThemeId,
+	      {
+		  ...draftCustomThemes,
+		  [draftActiveThemeId]: {
+		      ...draftCustomThemes[draftActiveThemeId],
+		      tagColours: {
+			  ...defaultThemeTagColoursFor (selectedTheme.baseTheme),
+		      },
+		  },
+	      },
+	  )
+      },
+      onResetTagColour: category => {
+	  if (selectedTheme.builtin || draftActiveThemeId === 'system')
+	    return
+
+	  applyDraftThemeSelection (
+	      draftActiveThemeId,
+	      {
+		  ...draftCustomThemes,
+		  [draftActiveThemeId]: {
+		      ...draftCustomThemes[draftActiveThemeId],
+		      tagColours: {
+			  ...draftCustomThemes[draftActiveThemeId].tagColours,
+			  [category]:
+			      defaultThemeTagColoursFor (selectedTheme.baseTheme)[category],
+		      },
+		  },
+	      },
+	  )
+      },
+      onThemeSubmit: handleThemeSubmit,
       settingsBaseErrors,
       settingsFieldErrors,
-      user,
   } : null
 
   return (
@@ -558,27 +737,22 @@ const SettingPage: FC<Props> = ({ user, setUser }) => {
 	  <title>設定 | {SITE_TITLE}</title>
 	</Helmet>
 
-	<div className="space-y-4 p-4">
+	<div className="mx-auto max-w-xl space-y-4 p-4 md:hidden">
-	  <div className="mx-auto max-w-xl space-y-4">
 	  <PageTitle>設定</PageTitle>
-	    <FieldError messages={error ? [error] : []}/>
+	  <FieldError messages={settingsError ? [settingsError] : []}/>
-	  </div>
+	  {loading ? 'Loading...' : (
-
-	  {user && loaded ? (
 	      <>
-		<div className="mx-auto max-w-xl space-y-6 md:hidden">
 		{sectionProps && (
 		    <>
 		      <AccountSection {...sectionProps}/>
 		      <ThemeSection {...sectionProps}/>
 		      <KeyboardSection/>
-			<EditingSection {...sectionProps}/>
+		    </>)}
-			<WikiSection {...sectionProps}/>
 	      </>)}
 	</div>
 
-		<div className={desktopTabRailClassName}>
+	<div className="hidden md:flex md:justify-center md:px-4">
-		  <div className={desktopTabRailInnerClassName}>
+	  <div className="grid w-full max-w-[58rem] grid-cols-[12rem_minmax(0,1fr)] gap-6">
 	    <div
 		role="tablist"
 		aria-label="設定区分"
@@ -608,23 +782,24 @@ const SettingPage: FC<Props> = ({ user, setUser }) => {
 		  </button>))}
 	    </div>
 
-		    <div className="w-[36rem] max-w-full">
+	    <div className="w-full max-w-xl justify-self-center space-y-4">
-		      {sectionProps && (
+	      <PageTitle>設定</PageTitle>
+	      <FieldError messages={settingsError ? [settingsError] : []}/>
+	      {loading ? 'Loading...' : (
 		  <div
 		      id={tabPanelId (activeTab)}
 		      role="tabpanel"
 		      aria-labelledby={tabButtonId (activeTab)}>
+		    {sectionProps && (
+			<>
 			  {activeTab === 'account' && <AccountSection {...sectionProps}/>}
 			  {activeTab === 'theme' && <ThemeSection {...sectionProps}/>}
 			  {activeTab === 'keyboard' && <KeyboardSection/>}
-			    {activeTab === 'editing' && <EditingSection {...sectionProps}/>}
+			</>)}
-			    {activeTab === 'wiki' && <WikiSection {...sectionProps}/>}
 		  </div>)}
 	    </div>
 	  </div>
 	</div>
-	      </>) : 'Loading...'}
-	</div>
 
 	<UserCodeDialogue
 	    visible={userCodeVsbl}

frontend/src/pages/wiki/WikiEditPage.tsx

@@ -8,7 +8,6 @@ import { useParams, useNavigate } from 'react-router-dom'
 import FieldError from '@/components/common/FieldError'
 import FormField from '@/components/common/FormField'
 import MainArea from '@/components/layout/MainArea'
-import { useUserSettings } from '@/components/users/UserSettingsProvider'
 import { toast } from '@/components/ui/use-toast'
 import { SITE_TITLE } from '@/config'
 import { apiGet, apiPut } from '@/lib/api'
@@ -25,27 +24,11 @@ import type { FC } from 'react'
 import type { User, WikiPage } from '@/types'
 
 const mdParser = new MarkdownIt
+const FIXED_WIKI_EDITOR_VIEW = { menu: true, md: true, html: true } as const
 
-type EditorView = {
+// `wiki_editor_mode` is still kept in backend settings, but the common
-    menu:  boolean
+// settings screen does not expose it at present. Until that UI returns, the
-    md:    boolean
+// editor stays on the fixed split view here.
-    html:  boolean }
-
-const editorView = (
-    mode: 'split' | 'write' | 'preview',
-): EditorView => {
-  switch (mode)
-  {
-  case 'write':
-    return { menu: true, md: true, html: false }
-
-  case 'preview':
-    return { menu: true, md: false, html: true }
-
-  default:
-    return { menu: true, md: true, html: true }
-  }
-}
 
 type Props = { user: User | null }
 
@@ -54,7 +37,6 @@ type WikiFormField = 'title' | 'body'
 
 const WikiEditPage: FC<Props> = ({ user }) => {
   const editable = canEditContent (user)
-  const { settings } = useUserSettings ()
 
   const { id } = useParams ()
 
@@ -137,7 +119,7 @@ const WikiEditPage: FC<Props> = ({ user }) => {
 		  {() => (
 		      <MdEditor value={body}
 				style={{ height: '500px' }}
-				config={{ view: editorView (settings.wikiEditorMode) }}
+				config={{ view: FIXED_WIKI_EDITOR_VIEW }}
 				renderHTML={text => mdParser.render (text)}
 				onChange={({ text }) => setBody (text)}/>)}
 		</FormField>

frontend/src/pages/wiki/WikiNewPage.tsx

@@ -9,7 +9,6 @@ import { useLocation, useNavigate } from 'react-router-dom'
 import FieldError from '@/components/common/FieldError'
 import FormField from '@/components/common/FormField'
 import MainArea from '@/components/layout/MainArea'
-import { useUserSettings } from '@/components/users/UserSettingsProvider'
 import { toast } from '@/components/ui/use-toast'
 import { SITE_TITLE } from '@/config'
 import { apiPost } from '@/lib/api'
@@ -23,27 +22,11 @@ import 'react-markdown-editor-lite/lib/index.css'
 import type { User, WikiPage } from '@/types'
 
 const mdParser = new MarkdownIt
+const FIXED_WIKI_EDITOR_VIEW = { menu: true, md: true, html: true } as const
 
-type EditorView = {
+// `wiki_editor_mode` is still kept in backend settings, but the common
-    menu:  boolean
+// settings screen does not expose it at present. Until that UI returns, the
-    md:    boolean
+// editor stays on the fixed split view here.
-    html:  boolean }
-
-const editorView = (
-    mode: 'split' | 'write' | 'preview',
-): EditorView => {
-  switch (mode)
-  {
-  case 'write':
-    return { menu: true, md: true, html: false }
-
-  case 'preview':
-    return { menu: true, md: false, html: true }
-
-  default:
-    return { menu: true, md: true, html: true }
-  }
-}
 
 type Props = { user: User | null }
 
@@ -52,7 +35,6 @@ type WikiFormField = 'title' | 'body'
 
 const WikiNewPage: FC<Props> = ({ user }) => {
   const editable = canEditContent (user)
-  const { settings } = useUserSettings ()
 
   const location = useLocation ()
   const navigate = useNavigate ()
@@ -115,7 +97,7 @@ const WikiNewPage: FC<Props> = ({ user }) => {
 	    {() => (
 		<MdEditor value={body}
 			  style={{ height: '500px' }}
-			  config={{ view: editorView (settings.wikiEditorMode) }}
+			  config={{ view: FIXED_WIKI_EDITOR_VIEW }}
 			  renderHTML={text => mdParser.render (text)}
 			  onChange={({ text }) => setBody (text)}/>)}
 	  </FormField>

frontend/tailwind.config.js

@@ -8,6 +8,7 @@ import { DARK_COLOUR_SHADE,
 const colours = Object.values (TAG_COLOUR)
 
 export default {
+    darkMode: 'class',
     content: ['./src/**/*.{html,js,ts,jsx,tsx,mdx}'],
     safelist: [...colours.map (c => `text-${ c }-${ LIGHT_COLOUR_SHADE }`),
 	       ...colours.map (c => `hover:text-${ c }-${ LIGHT_COLOUR_SHADE - 200 }`),