diff --git a/frontend/src/documents/DocumentInfoPanel.jsx b/frontend/src/documents/DocumentInfoPanel.jsx
index f1dc4f1..064125a 100644
--- a/frontend/src/documents/DocumentInfoPanel.jsx
+++ b/frontend/src/documents/DocumentInfoPanel.jsx
@@ -1,4 +1,4 @@
-import React, { useEffect, useMemo, useState } from 'react';
+import React, { useCallback, useEffect, useMemo, useState } from 'react';
 import DocumentSummarySection from './DocumentSummarySection';
 import { buildDocumentMetadataItems, extractDocumentMetadataPayload } from './documentMetadata';
 
@@ -16,6 +16,13 @@ const DocumentInfoPanel = ({
   resetKey = null,
   classNamePrefix = 'document-info',
   hideTabNavWhenSingle = true,
+  summaryPlacement = 'inline',
+  summaryTabLabel = 'Summary',
+  summaryTabId = 'summary',
+  leadingTabs = [],
+  trailingTabs = [],
+  tabsPlacement = 'top',
+  summaryLayout = 'default',
 }) => {
   const base = classNamePrefix;
 
@@ -92,29 +99,90 @@ const DocumentInfoPanel = ({
     };
   }, [contentConfig, contentEnabled, showContentTab, document?.id, resetKey]);
 
+  const renderSummarySection = useCallback(() => (
+    <DocumentSummarySection
+      document={document}
+      detailItems={metadataItems}
+      layout={summaryLayout}
+      {...summaryProps}
+    />
+  ), [document, summaryLayout, summaryProps, metadataItems]);
+
+  const renderDetailsSection = useCallback(() => (
+    <section className={`${base}__section`}>
+      {metadataItems.length ? (
+        <dl className={`${base}__section-list`}>
+          {metadataItems.map(({ label, value }) => (
+            <div className={`${base}__section-item`} key={label}>
+              <dt>{label}</dt>
+              <dd>{value || '—'}</dd>
+            </div>
+          ))}
+        </dl>
+      ) : (
+        <p className={`${base}__section-placeholder`}>No details available.</p>
+      )}
+    </section>
+  ), [base, metadataItems]);
+
+  const summaryInline = summaryPlacement !== 'tabs';
+
+  const summaryTab = useMemo(() => {
+    if (summaryPlacement !== 'tabs') {
+      return null;
+    }
+    return {
+      id: summaryTabId,
+      label: summaryTabLabel,
+      render: () => (
+        <div className={`${base}__summary-tab-content`}>
+          {renderSummarySection()}
+        </div>
+      ),
+    };
+  }, [summaryPlacement, summaryTabId, summaryTabLabel, base, renderSummarySection]);
+
+  const normalizedLeadingTabs = useMemo(
+    () => (Array.isArray(leadingTabs)
+      ? leadingTabs.filter((tab) => tab && tab.id && tab.label)
+      : []),
+    [leadingTabs],
+  );
+
+  const normalizedTrailingTabs = useMemo(
+    () => (Array.isArray(trailingTabs)
+      ? trailingTabs.filter((tab) => tab && tab.id && tab.label)
+      : []),
+    [trailingTabs],
+  );
+
+  const summaryNode = summaryInline
+    ? (
+        <>
+          {renderSummarySection()}
+          {renderDetailsSection()}
+        </>
+      )
+    : null;
+
   const visibleTabs = useMemo(() => {
     const tabsList = [];
 
-    tabsList.push({
-      id: 'details',
-      label: detailsTabLabel,
-      render: () => (
-        <section className={`${base}__section`}>
-          {metadataItems.length ? (
-            <dl className={`${base}__section-list`}>
-              {metadataItems.map(({ label, value }) => (
-                <div className={`${base}__section-item`} key={label}>
-                  <dt>{label}</dt>
-                  <dd>{value || '—'}</dd>
-                </div>
-              ))}
-            </dl>
-          ) : (
-            <p className={`${base}__section-placeholder`}>No details available.</p>
-          )}
-        </section>
-      ),
-    });
+    if (normalizedLeadingTabs.length) {
+      tabsList.push(...normalizedLeadingTabs);
+    }
+
+    if (summaryTab) {
+      tabsList.push(summaryTab);
+    }
+
+    if (summaryPlacement !== 'tabs') {
+      tabsList.push({
+        id: 'details',
+        label: detailsTabLabel,
+        render: () => renderDetailsSection(),
+      });
+    }
 
     if (showContentTab && contentConfig) {
       tabsList.push({
@@ -183,30 +251,38 @@ const DocumentInfoPanel = ({
     }
 
     if (metadataPayload) {
-      tabsList.push({
-        id: 'metadata',
-        label: metadataTabLabel,
-        render: () => (
-          <section className={`${base}__section ${base}__section--metadata-json`}>
-            <pre className={`${base}__metadata-json`}>
-              {JSON.stringify(metadataPayload, null, 2)}
-            </pre>
-          </section>
-        ),
-      });
+    tabsList.push({
+      id: 'metadata',
+      label: metadataTabLabel,
+      render: () => (
+        <section className={`${base}__section ${base}__section--metadata-json`}>
+          <pre className={`${base}__metadata-json`}>
+            {JSON.stringify(metadataPayload, null, 2)}
+          </pre>
+        </section>
+      ),
+    });
+    }
+
+    if (normalizedTrailingTabs.length) {
+      tabsList.push(...normalizedTrailingTabs);
     }
 
     return tabsList;
   }, [
     base,
     detailsTabLabel,
-    metadataItems,
     contentConfig,
     contentEnabled,
     contentState,
     metadataPayload,
     metadataTabLabel,
     showContentTab,
+    summaryTab,
+    normalizedLeadingTabs,
+    normalizedTrailingTabs,
+    summaryPlacement,
+    renderDetailsSection,
   ]);
 
   const fallbackTabId = useMemo(() => {
@@ -242,7 +318,7 @@ const DocumentInfoPanel = ({
     if (!isControlled) {
       setUncontrolledTab(fallbackTabId);
     }
-  }, [fallbackTabId, resetKey, isControlled]);
+  }, [fallbackTabId, isControlled]);
 
   useEffect(() => {
     if (isControlled && controlledActiveTab && !visibleTabs.some((tab) => tab.id === controlledActiveTab)) {
@@ -270,12 +346,40 @@ const DocumentInfoPanel = ({
   const singleTab = visibleTabs.length === 1 ? visibleTabs[0] : null;
   const shouldHideNav = hideTabNavWhenSingle && singleTab;
 
+  const tabNav = (
+    <div className={`${base}__tabs`} role="tablist" aria-label="Document details">
+      {visibleTabs.map((tab) => (
+        <button
+          key={tab.id}
+          type="button"
+          role="tab"
+          aria-selected={tab.id === activeTabId}
+          className={`${base}__tab${tab.id === activeTabId ? ' is-active' : ''}`}
+          onClick={() => handleTabSelect(tab.id)}
+        >
+          {tab.label}
+        </button>
+      ))}
+    </div>
+  );
+
+  const tabPanels = (
+    <div className={`${base}__tabpanes`}>
+      {visibleTabs.map((tab) => (
+        tab.id === activeTabId ? (
+          <div key={tab.id} role="tabpanel" className={`${base}__tabpanel`}>
+            {renderTabContent(tab, { document })}
+          </div>
+        ) : null
+      ))}
+    </div>
+  );
+
+  const tabsWrapperClass = `${base}__tabs-wrapper${tabsPlacement === 'bottom' ? ` ${base}__tabs-wrapper--bottom` : ''}`;
+
   return (
     <>
-      <DocumentSummarySection
-        document={document}
-        {...summaryProps}
-      />
+      {summaryNode}
       {shouldHideNav ? (
         <div className={`${base}__tabpanes ${base}__tabpanes--single`}>
           <div className={`${base}__tabpanel`}>
@@ -283,30 +387,11 @@ const DocumentInfoPanel = ({
           </div>
         </div>
       ) : (
-        <div className={`${base}__tabs-wrapper`}>
-          <div className={`${base}__tabs`} role="tablist" aria-label="Document details">
-            {visibleTabs.map((tab) => (
-              <button
-                key={tab.id}
-                type="button"
-                role="tab"
-                aria-selected={tab.id === activeTabId}
-                className={`${base}__tab${tab.id === activeTabId ? ' is-active' : ''}`}
-                onClick={() => handleTabSelect(tab.id)}
-              >
-                {tab.label}
-              </button>
-            ))}
-          </div>
-          <div className={`${base}__tabpanes`}>
-            {visibleTabs.map((tab) => (
-              tab.id === activeTabId ? (
-                <div key={tab.id} role="tabpanel" className={`${base}__tabpanel`}>
-                  {renderTabContent(tab, { document })}
-                </div>
-              ) : null
-            ))}
-          </div>
+        <div className={tabsWrapperClass}>
+          {tabsPlacement !== 'bottom' ? tabNav : null}
+          {tabsPlacement === 'bottom' ? tabPanels : null}
+          {tabsPlacement === 'bottom' ? tabNav : null}
+          {tabsPlacement !== 'bottom' ? tabPanels : null}
         </div>
       )}
     </>
diff --git a/frontend/src/documents/DocumentSummarySection.jsx b/frontend/src/documents/DocumentSummarySection.jsx
index 5793167..1d1319b 100644
--- a/frontend/src/documents/DocumentSummarySection.jsx
+++ b/frontend/src/documents/DocumentSummarySection.jsx
@@ -348,8 +348,11 @@ const DocumentSummarySection = ({
   onCorrespondentAdd,
   onCorrespondentRemove,
   onUpdateTitle,
-  onUpdateIssued
+  onUpdateIssued,
+  layout = 'default',
+  detailItems = [],
 }) => {
+  const isCompactLayout = layout === 'compact';
   const summary = useMemo(() => {
     if (!document) {
       return {
@@ -507,6 +510,204 @@ const DocumentSummarySection = ({
     return null;
   }
 
+  const TitleSection = () => (
+    editableTitle && isTitleEditing ? (
+      <form className="doc-title-edit" onSubmit={submitTitleEdit}>
+        <input
+          value={titleDraft}
+          onChange={(event) => {
+            setTitleDraft(event.target.value);
+            if (titleError) {
+              setTitleError(null);
+            }
+          }}
+          onKeyDown={(event) => {
+            if (event.key === 'Escape') {
+              event.preventDefault();
+              cancelTitleEdit();
+            }
+          }}
+          aria-label="Document title"
+          autoFocus
+          disabled={titleSaving}
+        />
+        <button type="submit" disabled={titleSaving}>
+          Save
+        </button>
+        <button
+          type="button"
+          className="secondary"
+          onClick={cancelTitleEdit}
+          disabled={titleSaving}
+        >
+          Cancel
+        </button>
+      </form>
+    ) : (
+      <>
+        <h3 className="doc-title-row__title">{summary.title}</h3>
+        {editableTitle ? (
+          <button
+            type="button"
+            className="icon-button"
+            onClick={startTitleEdit}
+            aria-label="Edit title"
+            title="Edit title"
+          >
+            <EditIcon className="icon-inline" />
+          </button>
+        ) : null}
+      </>
+    )
+  );
+
+  const issuedDisplay = editableIssued && isIssuedEditing ? (
+    <form className="doc-issued-edit" onSubmit={submitIssuedEdit}>
+      <input
+        type="date"
+        value={issuedDraft}
+        onChange={(event) => {
+          setIssuedDraft(event.target.value);
+          if (issuedError) {
+            setIssuedError(null);
+          }
+        }}
+        aria-label="Issued on"
+        disabled={issuedSaving}
+      />
+      <button type="submit" disabled={issuedSaving}>
+        Save
+      </button>
+      <button
+        type="button"
+        className="secondary"
+        onClick={cancelIssuedEdit}
+        disabled={issuedSaving}
+      >
+        Cancel
+      </button>
+    </form>
+  ) : (
+    <>
+      <span className="detail-meta__value">{issuedDateLabel || 'Not set'}</span>
+      {editableIssued ? (
+        <button
+          type="button"
+          className="icon-button"
+          onClick={startIssuedEdit}
+          aria-label={issuedDateLabel ? 'Edit issued date' : 'Set issued date'}
+          title={issuedDateLabel ? 'Edit issued date' : 'Set issued date'}
+        >
+          <EditIcon className="icon-inline" />
+        </button>
+      ) : null}
+    </>
+  );
+
+  const metaItems = [
+    {
+      key: 'issued',
+      label: 'Issued',
+      valueContent: issuedDisplay,
+      error: issuedError,
+    },
+    ...metaRows.map((row) => ({
+      key: row.key,
+      label: row.label,
+      fallbackValue: row.value,
+    })),
+  ];
+
+  const detailRows = Array.isArray(detailItems)
+    ? detailItems.map((item, index) => ({
+        key: `detail-${item?.label || index}`,
+        label: item?.label || '—',
+        fallbackValue: item?.value,
+      }))
+    : [];
+
+  const compactRows = [...metaItems, ...detailRows];
+
+  const renderTags = () => (
+    <section className="document-summary__section document-summary__section--tags">
+      <TagSection
+        tags={resolvedTags}
+        onRemove={
+          onTagRemove
+            ? (tag) => onTagRemove(document.id, tag.id)
+            : undefined
+        }
+        onAdd={
+          onTagAdd
+            ? ({ value, option }) => onTagAdd(document, value, { option })
+            : undefined
+        }
+        datalistOptions={tagOptions}
+        className="document-summary__tags"
+      />
+    </section>
+  );
+
+  const renderCorrespondents = () => (
+    <section className="document-summary__section document-summary__section--correspondents">
+      <CorrespondentSection
+        entries={resolvedCorrespondents}
+        onRemove={
+          onCorrespondentRemove
+            ? (entry) =>
+                onCorrespondentRemove({
+                  documentId: document.id,
+                  correspondentId: entry.id,
+                })
+            : undefined
+        }
+        onAdd={
+          onCorrespondentAdd
+            ? ({ name, option }) =>
+                onCorrespondentAdd({
+                  document,
+                  name,
+                  option,
+                })
+            : undefined
+        }
+        showCount
+        datalistOptions={correspondentOptions}
+        className="document-summary__correspondents"
+      />
+    </section>
+  );
+
+  if (isCompactLayout) {
+    return (
+      <div className="document-summary document-summary--compact">
+        <section className="document-summary__section document-summary__title-row">
+          <TitleSection />
+        </section>
+        {titleError ? <div className="status-inline error">{titleError}</div> : null}
+        {renderTags()}
+        {renderCorrespondents()}
+        {compactRows.length ? (
+          <section className="document-summary__section document-summary__meta document-summary__meta--compact">
+            <dl className="document-summary__details-list document-summary__details-list--meta">
+              {compactRows.map((item) => (
+                <div key={item.key} className="document-summary__details-row">
+                  <dt>{item.label}</dt>
+                  <dd>
+                    {item.valueContent != null && item.valueContent !== ''
+                      ? item.valueContent
+                      : item.fallbackValue || '—'}
+                  </dd>
+                  {item.error ? <div className="status-inline error">{item.error}</div> : null}
+                </div>
+              ))}
+            </dl>
+          </section>
+        ) : null}
+      </div>
+    );
+  }
+
   return (
     <div className="document-summary">
       <div className="doc-title-row">
@@ -552,62 +753,21 @@ const DocumentSummarySection = ({
                   className="icon-button"
                   onClick={startTitleEdit}
                   aria-label="Edit title"
-                  title="Edit title"
-                >
-                  <EditIcon className="icon-inline" />
-                </button>
-              ) : null}
-            </>
-          )}
-        </div>
+                title="Edit title"
+              >
+                <EditIcon className="icon-inline" />
+              </button>
+            ) : null}
+          </>
+        )}
       </div>
+    </div>
       {titleError ? <div className="status-inline error">{titleError}</div> : null}
 
       <div className="detail-meta">
         <div className="detail-meta__row">
           <span className="detail-meta__label">Issued:</span>
-          {editableIssued && isIssuedEditing ? (
-            <form className="doc-issued-edit" onSubmit={submitIssuedEdit}>
-              <input
-                type="date"
-                value={issuedDraft}
-                onChange={(event) => {
-                  setIssuedDraft(event.target.value);
-                  if (issuedError) {
-                    setIssuedError(null);
-                  }
-                }}
-                aria-label="Issued on"
-                disabled={issuedSaving}
-              />
-              <button type="submit" disabled={issuedSaving}>
-                Save
-              </button>
-              <button
-                type="button"
-                className="secondary"
-                onClick={cancelIssuedEdit}
-                disabled={issuedSaving}
-              >
-                Cancel
-              </button>
-            </form>
-          ) : (
-            <>
-              <span className="detail-meta__value">{issuedDateLabel || 'Not set'}</span>
-              {editableIssued ? (
-                <button
-                  type="button"
-                  className="icon-button"
-                  onClick={startIssuedEdit}
-                  aria-label={issuedDateLabel ? 'Edit issued date' : 'Set issued date'}
-                  title={issuedDateLabel ? 'Edit issued date' : 'Set issued date'}
-                >
-                  <EditIcon className="icon-inline" />
-                </button>
-              ) : null}
-            </>
-          )}
+          {issuedDisplay}
         </div>
         {issuedError ? <div className="status-inline error">{issuedError}</div> : null}
 
@@ -619,45 +779,9 @@ const DocumentSummarySection = ({
         ))}
       </div>
 
-      <TagSection
-        tags={resolvedTags}
-        onRemove={
-          onTagRemove
-            ? (tag) => onTagRemove(document.id, tag.id)
-            : undefined
-        }
-        onAdd={
-          onTagAdd
-            ? ({ value, option }) => onTagAdd(document, value, { option })
-            : undefined
-        }
-        datalistOptions={tagOptions}
-      />
+      {renderTags()}
 
-      <CorrespondentSection
-        entries={resolvedCorrespondents}
-        onRemove={
-          onCorrespondentRemove
-            ? (entry) =>
-                onCorrespondentRemove({
-                  documentId: document.id,
-                  correspondentId: entry.id,
-                })
-            : undefined
-        }
-        onAdd={
-          onCorrespondentAdd
-            ? ({ name, option }) =>
-                onCorrespondentAdd({
-                  document,
-                  name,
-                  option,
-                })
-            : undefined
-        }
-        showCount
-        datalistOptions={correspondentOptions}
-      />
+      {renderCorrespondents()}
     </div>
   );
 };
diff --git a/frontend/src/preview/DocumentViewerLayout.jsx b/frontend/src/preview/DocumentViewerLayout.jsx
index 964e5ea..1389c5a 100644
--- a/frontend/src/preview/DocumentViewerLayout.jsx
+++ b/frontend/src/preview/DocumentViewerLayout.jsx
@@ -1,4 +1,4 @@
-import React, { useMemo } from 'react';
+import React, { useCallback, useMemo } from 'react';
 import DocumentInfoPanel from '../documents/DocumentInfoPanel';
 import { DownloadIcon } from '../ui/icons';
 
@@ -13,7 +13,10 @@ const DocumentViewerLayout = ({
   defaultTabId = 'details',
   infoPanelProps = {},
   previewLoadingMessage = 'Preparing preview…',
+  layoutMode = 'split',
 }) => {
+  const isStacked = layoutMode === 'stacked';
+
   const previewContent = useMemo(() => {
     if (!document || !previewEntry?.url) {
       return null;
@@ -74,30 +77,65 @@ const DocumentViewerLayout = ({
     );
   }, [previewEntry, document]);
 
+  const renderViewportPane = useCallback(() => (
+    <div className="document-viewer__viewport">
+      {!previewEntry?.url ? (
+        <div className="document-viewer__message">{previewLoadingMessage}</div>
+      ) : (
+        previewContent
+      )}
+    </div>
+  ), [previewEntry?.url, previewLoadingMessage, previewContent]);
+
+  const viewportPane = renderViewportPane();
+
+  const stackedLeadingTabs = useMemo(() => (
+    isStacked
+      ? [
+          {
+            id: 'preview',
+            label: 'Preview',
+            render: () => renderViewportPane(),
+          },
+        ]
+      : []
+  ), [isStacked, renderViewportPane]);
+
+  const resolvedDefaultTabId = isStacked ? 'preview' : defaultTabId;
+  const summaryPlacement = 'tabs';
+  const tabsPlacement = isStacked ? 'bottom' : 'top';
+  const summaryLayout = 'compact';
+
+  const detailsPane = (
+    <div className="document-viewer__details-pane">
+      <div className="document-viewer__details">
+        <DocumentInfoPanel
+          document={document}
+          summaryProps={summaryProps}
+          metadataPayload={metadataPayload}
+          contentConfig={contentTabConfig}
+          defaultTabId={resolvedDefaultTabId}
+          classNamePrefix={classNamePrefix}
+          hideTabNavWhenSingle={false}
+          resetKey={resetKey || document?.id}
+          summaryPlacement={summaryPlacement}
+          summaryLayout={summaryLayout}
+          leadingTabs={stackedLeadingTabs}
+          tabsPlacement={tabsPlacement}
+          {...infoPanelProps}
+        />
+      </div>
+    </div>
+  );
+
+  if (isStacked) {
+    return detailsPane;
+  }
+
   return (
     <>
-      <div className="document-viewer__details-pane">
-        <div className="document-viewer__details">
-          <DocumentInfoPanel
-            document={document}
-            summaryProps={summaryProps}
-            metadataPayload={metadataPayload}
-            contentConfig={contentTabConfig}
-            defaultTabId={defaultTabId}
-            classNamePrefix={classNamePrefix}
-            hideTabNavWhenSingle={false}
-            resetKey={resetKey || document?.id}
-            {...infoPanelProps}
-          />
-        </div>
-      </div>
-      <div className="document-viewer__viewport">
-        {!previewEntry?.url ? (
-          <div className="document-viewer__message">{previewLoadingMessage}</div>
-        ) : (
-          previewContent
-        )}
-      </div>
+      {detailsPane}
+      {viewportPane}
     </>
   );
 };
diff --git a/frontend/src/preview/DocumentViewerPanel.jsx b/frontend/src/preview/DocumentViewerPanel.jsx
index 8a5cb61..2d92071 100644
--- a/frontend/src/preview/DocumentViewerPanel.jsx
+++ b/frontend/src/preview/DocumentViewerPanel.jsx
@@ -432,6 +432,7 @@ const DocumentViewerPanel = ({
           metadataPayload={metadataPayload}
           contentTabConfig={contentTabConfig}
           previewLoadingMessage="Loading preview…"
+          layoutMode={isStackedLayout ? 'stacked' : 'split'}
         />
       </section>
     </div>
diff --git a/frontend/src/styles/base/theme.css b/frontend/src/styles/base/theme.css
index 7f648c6..5bbee84 100644
--- a/frontend/src/styles/base/theme.css
+++ b/frontend/src/styles/base/theme.css
@@ -100,7 +100,7 @@
   font-size: 15px;
   --font-mono: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
 
-  --detail-panel-width: 30em;
+  --detail-panel-width: calc(100vw / 3);
   --documents-grid-title-size: 0.8rem;
 }
 
diff --git a/frontend/src/styles/detail/detail-panels.css b/frontend/src/styles/detail/detail-panels.css
index f5584c6..b718ca9 100644
--- a/frontend/src/styles/detail/detail-panels.css
+++ b/frontend/src/styles/detail/detail-panels.css
@@ -489,6 +489,88 @@
   gap: 0.25rem;
 }
 
+
+.document-summary--compact {
+  display: flex;
+  flex-direction: column;
+  gap: 1.25rem;
+}
+
+.document-summary__title-row {
+  display: flex;
+  align-items: center;
+  gap: 0.5rem;
+  flex-wrap: wrap;
+}
+
+.document-summary__meta {
+  display: flex;
+  flex-direction: column;
+  gap: 0.5rem;
+}
+
+.document-summary__meta-row {
+  display: flex;
+  align-items: center;
+  gap: 0.5rem;
+  flex-wrap: wrap;
+}
+
+.document-summary__meta-label {
+  color: var(--muted);
+}
+
+.document-summary__meta-value {
+  color: var(--fg);
+  display: inline-flex;
+  align-items: center;
+  gap: 0.35rem;
+}
+
+.document-summary__meta-value .detail-meta__value {
+  font-size: inherit;
+  color: inherit;
+}
+
+.document-summary__section {
+  padding: 0;
+}
+
+.tag-list.document-summary__tags,
+.correspondent-list.document-summary__correspondents {
+  margin-top: 0.25rem;
+}
+
+.document-summary__details {
+}
+
+.document-summary__details-list {
+  margin: 0;
+  padding: 0;
+  display: flex;
+  flex-direction: column;
+  gap: 1.25rem;
+}
+
+.document-summary__details-row {
+  display: flex;
+  flex-direction: column;
+  gap: 0.15rem;
+}
+
+.document-summary__details-row dt {
+  margin: 0;
+  font-size: 0.8rem;
+  color: var(--muted);
+  word-break: break-word;
+}
+
+.document-summary__details-row dd {
+  margin: 0;
+  font-size: 0.95rem;
+  word-break: break-word;
+}
+
 .detail-panel .doc-title-edit,
 .document-summary .doc-title-edit {
   display: flex;
@@ -773,7 +855,7 @@
 
 .detail-panel dt {
   font-weight: 600;
-  margin-top: 0.8rem;
+  margin-top: 0;
 }
 
 .detail-panel dd {
@@ -786,7 +868,6 @@
   display: flex;
   flex-wrap: wrap;
   gap: 0.5rem;
-  margin: 1rem 0;
   align-items: center;
 }
 
diff --git a/frontend/src/styles/documents/viewer.css b/frontend/src/styles/documents/viewer.css
index 0037025..6d2dfbe 100644
--- a/frontend/src/styles/documents/viewer.css
+++ b/frontend/src/styles/documents/viewer.css
@@ -43,7 +43,7 @@
   display: flex;
   flex-direction: column;
   gap: 0.5rem;
-  padding: 0.5rem 1rem 1rem;
+  padding: 0.5rem 1rem 0.5rem;
   overflow: auto;
 }
 
@@ -53,7 +53,8 @@
   flex-direction: column;
   justify-content: center;
   align-items: center;
-  max-height: calc(var(--document-viewer-portrait-height-ratio) * 100vh);
+  flex: 1;
+  min-height: 0;
   order: -1;
 }
 
@@ -189,6 +190,15 @@
   min-height: 0;
 }
 
+.document-viewer__tabs-wrapper--bottom .document-viewer__tabpanes {
+  order: 1;
+}
+
+.document-viewer__tabs-wrapper--bottom .document-viewer__tabs {
+  order: 2;
+  margin-top: 0.75rem;
+}
+
 .document-viewer__section {
   display: flex;
   flex-direction: column;
@@ -268,28 +278,37 @@
   font-size: 0.85rem;
   line-height: 1.35;
   overflow: auto;
+  word-break: break-word;
+  overflow-wrap: anywhere;
+  white-space: pre-wrap;
 }
 
 .document-viewer__tabs {
-  display: inline-flex;
-  align-items: center;
-  gap: 0.5rem;
-  border-bottom: 1px solid var(--outline-subtle);
+  display: flex;
+  align-items: stretch;
+  gap: 0.25rem;
+  padding: 0.25rem;
+  border-radius: 999px;
+  background: var(--surface-overlay, var(--surface));
+  border: 1px solid var(--outline-subtle);
+  box-shadow: var(--panel-shadow-soft, none);
 }
 
 .document-viewer__tab {
   appearance: none;
   border: none;
   background: transparent;
-  padding: 0.4rem 0.75rem;
+  padding: 0.35rem 0.9rem;
   font-size: 0.85rem;
   font-weight: 500;
   color: var(--muted);
   cursor: pointer;
-  border-bottom: 2px solid transparent;
   transition:
     color 120ms ease,
-    border-color 120ms ease;
+    background-color 120ms ease;
+  border-radius: 999px;
+  flex: 1;
+  text-align: center;
 }
 
 .document-viewer__tab:hover,
@@ -298,8 +317,8 @@
 }
 
 .document-viewer__tab.is-active {
-  color: var(--accent);
-  border-color: var(--accent);
+  color: var(--accent-strong, var(--accent));
+  background: var(--accent-soft);
 }
 
 .document-viewer__tabpanes {
@@ -308,6 +327,10 @@
   display: flex;
 }
 
+.document-viewer--stacked .document-viewer__tabpanes {
+  overflow: auto;
+}
+
 .document-viewer__tabpanes--single {
   flex: 1;
   min-height: 0;
@@ -345,7 +368,7 @@
   display: flex;
   position: relative;
   overflow: hidden;
-  align-items: flex-start;
+  align-items: stretch;
   justify-content: flex-start;
   max-height: 100%;
   grid-area: viewport;
@@ -369,12 +392,11 @@
 }
 
 .document-viewer--stacked .document-viewer__object:not(.document-viewer__object--image) {
-  height: calc(var(--document-viewer-portrait-height-ratio) * 100vh);
-  max-height: 100%;
+  height: 100%;
 }
 
 .document-viewer--stacked .document-viewer__object--image {
-  height: auto;
+  max-height: 100%;
 }
 
 .document-viewer__unsupported {
@@ -408,3 +430,6 @@
   width: 1rem;
   height: 1rem;
 }
+.document-viewer__summary-tab-content {
+  padding-top: 0.5rem;
+}