diff --git a/frontend/src/components/counts/CountsAxes.tsx b/frontend/src/components/counts/CountsAxes.tsx
index 11b8900..bfff91f 100644
--- a/frontend/src/components/counts/CountsAxes.tsx
+++ b/frontend/src/components/counts/CountsAxes.tsx
@@ -2,7 +2,7 @@ import SortableList from '@/components/common/SortableList'
 import { countsAxisFields, countsFilterFields, readCountsJSON, useCountsDefinition }
     from '@/lib/countsDefinitions'
 import { useClientMotion } from '@/lib/useClientMotion'
-import { inputClass } from '@/lib/utils'
+import { cn, inputClass } from '@/lib/utils'
 import { useUITranslation } from '@/lib/useUITranslation'
 
 import type { CountsAxis } from '@/lib/countsDefinitions'
@@ -43,8 +43,12 @@ const CountsAxes = ({ params, update }: {
         <div className="rounded border dark:border-slate-700">{content}</div>
       </fieldset>} renderItem={(id, group) => {
         const axis = axes.find (axis => axis.field === id)
-        return <div className="flex flex-wrap items-center gap-2 text-sm">
-          {group === 'available' && <span className="inline-flex gap-1">
+	return <div className={cn ('flex items-center gap-2 text-sm',
+	    group !== 'available' && 'flex-wrap')}>
+	  <span className="min-w-0 flex-1 break-words">
+	    {label (available.find (field => field.key === id)?.label ?? 'axis')}
+	  </span>
+	  {group === 'available' && <span className="ml-auto inline-flex shrink-0 gap-1">
             {(['rows', 'cols'] as const).map (target => <button key={target} type="button"
                 className="h-7 w-7 rounded-full border border-slate-300 bg-slate-100
                 text-xs text-slate-700 hover:bg-blue-100 hover:text-blue-900
@@ -58,7 +62,6 @@ const CountsAxes = ({ params, update }: {
                 lang={message ('axisPlace').language} onClick={() => place (id, target)}>
               {label (target)}</button>)}
           </span>}
-          {label (available.find (field => field.key === id)?.label ?? 'axis')}
           {group !== 'available' && <>
             {countsFilterFields (definition)[id] === 'datetime' && <select
                 className={inputClass (false, 'w-auto py-0')}
diff --git a/frontend/src/components/counts/CountsControls.tsx b/frontend/src/components/counts/CountsControls.tsx
index a40c3ff..2b9d88d 100644
--- a/frontend/src/components/counts/CountsControls.tsx
+++ b/frontend/src/components/counts/CountsControls.tsx
@@ -64,23 +64,28 @@ const CountsControls = (
     execute (normaliseCountsParams (resource, next))
   }}>
     <div className="flex flex-wrap items-center gap-2 border-b pb-1 dark:border-slate-700">
-      {history ? <>
-        {['from', 'through'].map (key => <label key={key}
-            className="flex flex-wrap items-center gap-1 text-sm">
-          {label (key)}<DateTimeField precision="second" value={draft.get (key) ?? ''}
-              aria-label={message (key).text} onChange={value => update (key, value ?? '')}/>
-        </label>)}
-      </> : <div className="flex flex-wrap items-center gap-1 text-sm">
+      {history ? <div className="flex min-w-0 max-w-full items-center gap-1">
+	<DateTimeField precision="second" value={draft.get ('from') ?? ''}
+	    aria-label={message ('from').text} lang={message ('from').language}
+	    className="min-w-0 flex-1" onChange={value => update ('from', value ?? '')}/>
+	<span className="shrink-0">{label ('periodSeparator')}</span>
+	<DateTimeField precision="second" value={draft.get ('through') ?? ''}
+	    aria-label={message ('through').text} lang={message ('through').language}
+	    className="min-w-0 flex-1" onChange={value => update ('through', value ?? '')}/>
+      </div> : <div className="flex flex-wrap items-center gap-1 text-sm">
         {label ('referenceAt')}<HelpPopover label={message ('referenceAt')}>
           {label ('referenceHelp')}</HelpPopover>
-	<label className="inline-flex items-center gap-1">
-	  <input type="checkbox" checked={countsUseLatest (draft)}
-	      onChange={event => update ('current', event.target.checked ? '1' : '0')}/>
-	  {label ('latest')}</label>
-	<DateTimeField precision="second" disabled={countsUseLatest (draft)}
-	    value={draft.get ('at') ?? ''}
-	    aria-label={message ('referenceAt').text} lang={message ('referenceAt').language}
-            onChange={value => update ('at', value ?? '')}/>
+	<div className="flex min-w-0 max-w-full items-center gap-1">
+	  <DateTimeField precision="second" disabled={countsUseLatest (draft)}
+	      className="min-w-0 flex-1"
+	      value={draft.get ('at') ?? ''}
+	      aria-label={message ('referenceAt').text} lang={message ('referenceAt').language}
+	      onChange={value => update ('at', value ?? '')}/>
+	  <label className="inline-flex shrink-0 items-center gap-1">
+	    <input type="checkbox" checked={countsUseLatest (draft)}
+		onChange={event => update ('current', event.target.checked ? '1' : '0')}/>
+	    {label ('latest')}</label>
+	</div>
       </div>}
     </div>
     <div className="flex flex-wrap items-center gap-2 border-b py-1 dark:border-slate-700">
diff --git a/frontend/src/components/counts/CountsNestedTable.tsx b/frontend/src/components/counts/CountsNestedTable.tsx
index 3093b3c..8093050 100644
--- a/frontend/src/components/counts/CountsNestedTable.tsx
+++ b/frontend/src/components/counts/CountsNestedTable.tsx
@@ -4,7 +4,7 @@ import CountsSortHeader from '@/components/counts/CountsSortHeader'
 import CountsSelectableTable from '@/components/counts/CountsSelectableTable'
 import { changeCountSort, readCountSort, selectedCountChildren,
 	 writeCountSort, orderedCountFields } from '@/lib/counts'
-import { countsLogicalName, countsNestedExport,
+import { countsLogicalName, countsNestedClipboardTable, countsNestedExport,
 	 countsNestedOrder, countsNestedText } from '@/lib/countsDisplay'
 import { useLocale } from '@/lib/useLocale'
 import { useUITranslation } from '@/lib/useUITranslation'
@@ -67,6 +67,7 @@ const CountsNestedTable = (
 		className="relative isolate max-h-72 w-full min-w-0 overflow-auto">
 	      <CountsSelectableTable family={path} columns={columns.map (field => field.key)}
 		  identity={`${path}:${params}`} name={title}
+		  copyTable={() => countsNestedClipboardTable (rows, fields, path, params, locale)}
 		  className="text-xs">
 		<thead className="sticky top-0 z-10 bg-background text-foreground
 		    dark:bg-background dark:text-foreground"><tr>
diff --git a/frontend/src/components/counts/CountsResults.tsx b/frontend/src/components/counts/CountsResults.tsx
index ca94d72..7a7c298 100644
--- a/frontend/src/components/counts/CountsResults.tsx
+++ b/frontend/src/components/counts/CountsResults.tsx
@@ -8,8 +8,8 @@ import CountsSelectableTable from '@/components/counts/CountsSelectableTable'
 import PostThumbnailPreview from '@/components/posts/PostThumbnailPreview'
 import { changeCountSort, countColumns, countsRequestParams, fieldsForCounts,
 	 readCountSort, selectedCountColumns, writeCountSort } from '@/lib/counts'
-import { countsCellCopy, countsCellText, countsImageURL, countsNestedRows }
-    from '@/lib/countsDisplay'
+import { countsCellCopy, countsCellText, countsDetailClipboardTable,
+	 countsImageURL, countsNestedRows } from '@/lib/countsDisplay'
 import useDialogue from '@/lib/dialogues/useDialogue'
 import { useLocale } from '@/lib/useLocale'
 import { useCountsDefinition } from '@/lib/countsDefinitions'
@@ -101,6 +101,9 @@ const CountsResults = (
 	{tableColumns.length === 0 ? <p>{label ('nested.noColumns')}</p> : (
 	    <CountsSelectableTable family={resource}
 		columns={tableColumns}
+		copyTable={() => countsDetailClipboardTable (data.versions ?? [],
+		    columns.map (column => fields.find (field => field.key === column)!),
+		    params, locale, rowNumbers ? (data.page - 1) * data.limit + 1 : null)}
 		identity={`${resource}:${countsRequestParams (params)}:${tableColumns.join (',')}:${
 		    (data.versions ?? []).map (row => row.id)}`}
 		className="text-left text-sm">
diff --git a/frontend/src/components/counts/CountsSelectableTable.tsx b/frontend/src/components/counts/CountsSelectableTable.tsx
index 075043e..4ddb4a9 100644
--- a/frontend/src/components/counts/CountsSelectableTable.tsx
+++ b/frontend/src/components/counts/CountsSelectableTable.tsx
@@ -8,6 +8,7 @@ import { useUITranslation } from '@/lib/useUITranslation'
 
 import type { ClipboardEvent, ReactNode } from 'react'
 
+import type { CountsClipboardTable } from '@/lib/countsClipboard'
 import type { CountsMenuAction } from '@/components/counts/CountsCellMenu'
 
 type Point = { row: number; column: number }
@@ -20,13 +21,14 @@ const cellAt = (table: HTMLTableElement, point: Point) =>
 
 
 const CountsSelectableTable = (
-    { family, columns, identity, children, className, name }: {
+    { family, columns, identity, children, className, name, copyTable }: {
 	family: string
 	columns: string[]
 	identity: string
 	children: ReactNode
 	className?: string
-	name?: { text: string; language: string } },
+	name?: { text: string; language: string }
+	copyTable?: () => CountsClipboardTable },
 ) => {
   const id = useId ()
   const root = useRef<HTMLTableElement> (null)
@@ -103,6 +105,14 @@ const CountsSelectableTable = (
   }
   const clipboard = (headers = false) => {
     if (bounds == null || root.current == null) return null
+    if (copyTable != null)
+    {
+      const table = copyTable ()
+      return countsClipboard ({
+	  columns: table.columns.slice (bounds.left, bounds.right + 1),
+	  rows: table.rows.slice (bounds.top, bounds.bottom + 1)
+	      .map (row => row.slice (bounds.left, bounds.right + 1)) }, headers)
+    }
     const rows: string[][] = []
     for (let row = bounds.top; row <= bounds.bottom; ++row)
     {
diff --git a/frontend/src/lib/counts.ts b/frontend/src/lib/counts.ts
index 562c294..5db1208 100644
--- a/frontend/src/lib/counts.ts
+++ b/frontend/src/lib/counts.ts
@@ -269,6 +269,10 @@ export const selectedCountFields = (
 }
 
 
+export const defaultCountsMode = (definition: string | null): 'summary' | 'details' =>
+    definition === 'history' ? 'details' : 'summary'
+
+
 export const normaliseCountsParams = (
     resource: CountsResource,
     source: URLSearchParams,
@@ -276,10 +280,11 @@ export const normaliseCountsParams = (
   const params = new URLSearchParams (source)
   if (!params.has ('definition'))
     params.set ('definition', params.get ('basis') === 'history' ? 'history' : 'latest')
+  if (!params.has ('current')) params.set ('current', params.get ('at') ? '0' : '1')
   const legacy = params.get ('mode')
   if (['state', 'trend', 'snapshot'].includes (legacy ?? ''))
     params.set ('mode', legacy === 'snapshot' ? 'details' : 'summary')
-  if (!params.has ('mode')) params.set ('mode', 'summary')
+  if (!params.has ('mode')) params.set ('mode', defaultCountsMode (params.get ('definition')))
   if (!params.has ('rows') && params.has ('axis'))
   {
     const field = params.get ('axis') === 'month' ? 'created_at' : params.get ('axis')!
@@ -305,8 +310,7 @@ export const isCountsState = (params: URLSearchParams): boolean =>
 
 
 export const countsUseLatest = (params: URLSearchParams): boolean =>
-    params.get ('current') === '1'
-    || (params.get ('current') !== '0' && !params.get ('at'))
+    params.get ('current') !== '0'
 
 
 export const countsRequestParams = (params: URLSearchParams): URLSearchParams => {
diff --git a/frontend/src/lib/countsClipboard.ts b/frontend/src/lib/countsClipboard.ts
index 1715f88..070a8c9 100644
--- a/frontend/src/lib/countsClipboard.ts
+++ b/frontend/src/lib/countsClipboard.ts
@@ -1,11 +1,67 @@
 export type CountsClipboard = { text: string; html: string }
+export type CountsClipboardColumn = { label: string; children?: CountsClipboardColumn[] }
+export type CountsClipboardCell = string | CountsClipboardTable
+export type CountsClipboardTable = {
+    columns: CountsClipboardColumn[]; rows: CountsClipboardCell[][] }
 
 
 const escapeHTML = (value: string): string => value.replace (/[&<>"']/g, character =>
     ({ '&': '&amp;', '<': '&lt;', '>': '&gt;', '"': '&quot;', "'": '&#39;' })[character]!)
 
 
-export const countsClipboard = (rows: string[][], headers = false): CountsClipboard => {
+const columnWidth = (column: CountsClipboardColumn): number =>
+    column.children?.reduce ((sum, child) => sum + columnWidth (child), 0) || 1
+
+
+const headerDepth = (columns: CountsClipboardColumn[]): number =>
+    columns.length === 0 ? 0 : 1 + Math.max (0, ...columns.map (column =>
+	headerDepth (column.children ?? [])))
+
+
+const headerRows = (columns: CountsClipboardColumn[]): string[][] => {
+  const width = columns.reduce ((sum, column) => sum + columnWidth (column), 0)
+  const rows = Array.from ({ length: headerDepth (columns) },
+      () => Array<string> (width).fill (''))
+  const place = (fields: CountsClipboardColumn[], row: number, offset: number) => {
+    for (const field of fields)
+    {
+      rows[row][offset] = field.label
+      if (field.children?.length) place (field.children, row + 1, offset)
+      offset += columnWidth (field)
+    }
+  }
+  if (columns.length) place (columns, 0, 0)
+  return rows
+}
+
+
+const dataRows = (
+    table: CountsClipboardTable,
+    columns = table.columns,
+): string[][] => {
+  if (columns.length === 0) return []
+  return table.rows.flatMap (record => {
+    const blocks = columns.map ((column, index) => {
+      const value = record[index] ?? ''
+      return typeof value === 'string' ? [[value]]
+	  : dataRows (value, column.children ?? value.columns)
+    })
+    const height = Math.max (1, ...blocks.map (block => block.length))
+    // Sibling arrays share the parent row's height; they never form a Cartesian product.
+    return Array.from ({ length: height }, (_, row) => columns.flatMap ((column, index) =>
+	Array.from ({ length: columnWidth (column) }, (_, offset) =>
+	    blocks[index][row]?.[offset] ?? '')))
+  })
+}
+
+
+export const countsClipboard = (
+    source: string[][] | CountsClipboardTable,
+    headers = false,
+): CountsClipboard => {
+  const headings = !Array.isArray (source) && headers ? headerRows (source.columns) : []
+  const rows = Array.isArray (source) ? source : [...headings, ...dataRows (source)]
+  const headingCount = Array.isArray (source) ? (headers ? 1 : 0) : headings.length
   // Excel accepts quoted TSV fields only when delimiters or quotes require them.
   // Prefix formula-like text in both representations, including leading whitespace.
   const safe = rows.map (row => row.map (value => /^\s*[=+@-]/.test (value)
@@ -13,7 +69,7 @@ export const countsClipboard = (rows: string[][], headers = false): CountsClipbo
   const text = safe.map (row => row.map (value => /[\t\r\n"]/.test (value)
       ? `"${value.replaceAll ('"', '""')}"` : value).join ('\t')).join ('\r\n')
   const html = '<html><body><table>' + safe.map ((row, index) => '<tr>' + row.map (value => {
-    const tag = headers && index === 0 ? 'th' : 'td'
+    const tag = index < headingCount ? 'th' : 'td'
     // Preserve time strings, leading zeroes, and user text instead of inferring dates/formulae.
     const numeric = value.length <= 15 && /^(?:0|[1-9]\d*)(?:\.\d+)?$/.test (value)
     const style = numeric ? 'white-space:pre-wrap' : 'white-space:pre-wrap;mso-number-format:"\\@"'
diff --git a/frontend/src/lib/countsDisplay.ts b/frontend/src/lib/countsDisplay.ts
index 239491b..941b237 100644
--- a/frontend/src/lib/countsDisplay.ts
+++ b/frontend/src/lib/countsDisplay.ts
@@ -5,6 +5,8 @@ import { localisedDateString, msToTime, originalCreatedAtString } from '@/lib/ut
 
 import type { CountColumn, CountField, CountRecord,
 	      CountsResource, CountsVersion } from '@/lib/counts'
+import type { CountsClipboardCell, CountsClipboardColumn, CountsClipboardTable }
+    from '@/lib/countsClipboard'
 import type { CountsDefinition } from '@/lib/countsDefinitions'
 import type { LocaleCode } from '@/lib/locales'
 
@@ -278,3 +280,61 @@ export const countsExportLabels = (
   labels.notRegistered = translateUIMessage ('notRegistered', 'counts', locale).text
   return labels
 }
+
+
+const clipboardColumns = (
+    fields: CountField[],
+    path: string,
+    params: URLSearchParams,
+    locale: LocaleCode,
+): CountsClipboardColumn[] => {
+  const selected = selectedCountChildren (params)
+  return orderedCountFields (fields, params, path)
+      .filter (field => selected.has (`${path}.${field.key}`))
+      .map (field => ({ label: translateUIMessage (field.label, 'counts', locale).text,
+	  children: field.children == null ? undefined : clipboardColumns (
+	      field.children, `${path}.${field.key}`, params, locale) }))
+}
+
+
+export const countsNestedClipboardTable = (
+    rows: CountRecord[],
+    fields: CountField[],
+    path: string,
+    params: URLSearchParams,
+    locale: LocaleCode,
+): CountsClipboardTable => {
+  const selected = selectedCountChildren (params)
+  const columns = orderedCountFields (fields, params, path)
+      .filter (field => selected.has (`${path}.${field.key}`))
+  return {
+      columns: clipboardColumns (fields, path, params, locale),
+      rows: countsNestedOrder (rows, path, params, locale).map (row => columns.map (field =>
+	  field.children == null ? countsLogicalName (row, field.key, locale).text
+	      : countsNestedClipboardTable (row[field.key] as CountRecord[] ?? [],
+		  field.children, `${path}.${field.key}`, params, locale))) }
+}
+
+
+export const countsDetailClipboardTable = (
+    rows: CountsVersion[],
+    fields: CountField[],
+    params: URLSearchParams,
+    locale: LocaleCode,
+    rowStart: number | null = null,
+): CountsClipboardTable => {
+  const columns = fields.map (field => ({
+      label: translateUIMessage (field.label, 'counts', locale).text,
+      children: field.children == null ? undefined : clipboardColumns (
+	  field.children, field.key, params, locale) }))
+  if (rowStart != null)
+    columns.unshift ({ label: translateUIMessage ('rowNumbers', 'counts', locale).text,
+	children: undefined })
+  return { columns, rows: rows.map ((row, index) => {
+    const cells: CountsClipboardCell[] = fields.map (field => field.children == null
+	? countsCellText (row, field.key, locale, params)
+	: countsNestedClipboardTable (countsNestedRows (row, field.key), field.children,
+	    field.key, params, locale))
+    return rowStart == null ? cells : [String (rowStart + index), ...cells]
+  }) }
+}
diff --git a/frontend/src/locales/ja/counts.json b/frontend/src/locales/ja/counts.json
index 2e32ae3..f2541fe 100644
--- a/frontend/src/locales/ja/counts.json
+++ b/frontend/src/locales/ja/counts.json
@@ -35,8 +35,8 @@
     "deprecated": "廃止状態",
     "latest": "最新フラグ",
     "thumbnailURL": "サムネール元 URL",
-    "originalFrom": "オリジナルの投稿日時（開始境界）",
-    "originalBefore": "オリジナルの投稿日時（終了境界・未満）",
+    "originalFrom": "オリジナルの投稿日時（以降）",
+    "originalBefore": "オリジナルの投稿日時（より前）",
     "language": "言語",
     "kind": "内部・外部",
     "sections": "記載区間",
@@ -136,8 +136,8 @@
   "history": "履歴",
   "referenceAt": "基準日時",
   "referenceHelp": "指定した日時における各データの最新版を集計・表示します。空欄の場合は現在の最新版を使用します。",
-  "from": "開始（以上）",
-  "through": "終了（以下）",
+  "from": "開始",
+  "through": "終了",
   "axisItems": "項目一覧",
   "rows": "行",
   "cols": "列",
@@ -210,13 +210,14 @@
     "parent_post_ids": "親投稿",
     "parent_tag_ids": "上位タグ",
     "video_ms": "動画時間",
-    "original_created_from": "オリジナルの投稿日時（開始境界）",
-    "original_created_before": "オリジナルの投稿日時（終了境界）",
+    "original_created_from": "オリジナルの投稿日時（以降）",
+    "original_created_before": "オリジナルの投稿日時（より前）",
     "deprecated_at": "廃止日時",
     "section_name": "節の名称",
     "children": "子項目",
     "profile": "出力設定",
     "path": "出力パス"
   },
-  "rowNumbers": "行番号"
+  "rowNumbers": "行番号",
+  "periodSeparator": "〜"
 }
diff --git a/frontend/src/pages/CountsResourcePage.tsx b/frontend/src/pages/CountsResourcePage.tsx
index 4c0a927..6401734 100644
--- a/frontend/src/pages/CountsResourcePage.tsx
+++ b/frontend/src/pages/CountsResourcePage.tsx
@@ -14,7 +14,7 @@ import Pagination from '@/components/common/Pagination'
 import MainArea from '@/components/layout/MainArea'
 import SidebarComponent from '@/components/layout/SidebarComponent'
 import { Button } from '@/components/ui/button'
-import { countsRequestParams, exportCounts, fieldsForCounts, fetchCounts,
+import { countsRequestParams, defaultCountsMode, exportCounts, fieldsForCounts, fetchCounts,
 	 isCountsState, normaliseCountsParams, selectedCountColumns } from '@/lib/counts'
 import { countsExportLabels } from '@/lib/countsDisplay'
 import { CountsDefinitionContext, countsAxisFields, countsResources, countsFieldLabel,
@@ -163,8 +163,9 @@ const CountsResourceContent = ({ resource }: { resource: CountsResource }) => {
                   <AnimatedCollapse open={expanded.has (target)} id={`counts-definition-${target}`}>
                   <ul className="ml-3">
                     {['latest', 'history'].map (definition => {
-                      const next = new URLSearchParams ({ definition, mode })
-		      for (const key of ['timezone', 'at', 'current'])
+		      const next = new URLSearchParams ({
+			  definition, mode: defaultCountsMode (definition) })
+		      for (const key of ['timezone', 'at', 'current', 'row_numbers'])
                         if (params.get (key)) next.set (key, params.get (key)!)
                       const active = target === resource
                           && params.get ('definition') === definition