diff --git a/frontend/app.js b/frontend/app.js
index 55d8485..3eee3f6 100644
--- a/frontend/app.js
+++ b/frontend/app.js
@@ -7828,6 +7828,12 @@
     FindInPageManager.init();
     ContextMenuManager.init();
 
+    // Mermaid.js init
+    import('./mermaid-viewer.js').then(function(m) {
+      m.initMermaid();
+      m.setupFocusMode();
+    });
+
     // Check auth status first
     const authOk = await AuthManager.initAuth();
 
diff --git a/frontend/index.html b/frontend/index.html
index 8837a8a..d5aecaf 100644
--- a/frontend/index.html
+++ b/frontend/index.html
@@ -61,6 +61,7 @@
         />
         <script src="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/11.9.0/highlight.min.js"></script>
         <script src="https://unpkg.com/lucide@0.344.0/dist/umd/lucide.min.js"></script>
+        <script src="https://cdn.jsdelivr.net/npm/mermaid@11/dist/mermaid.min.js"></script>
         <script type="importmap">
             {
                 "imports": {
diff --git a/frontend/js/mermaid-viewer.js b/frontend/js/mermaid-viewer.js
new file mode 100644
index 0000000..375b5c6
--- /dev/null
+++ b/frontend/js/mermaid-viewer.js
@@ -0,0 +1,360 @@
+/**
+ * Mermaid.js integration for ObsiGate.
+ *
+ * Handles initialization, rendering, templates, zoom/pan,
+ * fullscreen, focus mode, theme sync, and Obsidian compatibility.
+ *
+ * Usage: import { initMermaid, renderMermaidBlocks } from './mermaid-viewer.js';
+ */
+import { safeCreateIcons } from './utils.js';
+
+// ---------------------------------------------------------------------------
+// Configuration (#20)
+// ---------------------------------------------------------------------------
+
+var _mermaidReady = false;
+var _currentTheme = 'default';
+
+export function initMermaid() {
+  if (typeof mermaid === 'undefined') {
+    console.warn('[Mermaid] library not loaded');
+    return;
+  }
+  mermaid.initialize({
+    startOnLoad: false,
+    securityLevel: 'strict',
+    theme: _currentTheme,
+    fontFamily: 'inherit',
+  });
+  _mermaidReady = true;
+}
+
+export function updateMermaidTheme(isDark) {
+  _currentTheme = isDark ? 'dark' : 'default';
+  if (_mermaidReady) {
+    mermaid.initialize({
+      startOnLoad: false,
+      securityLevel: 'strict',
+      theme: _currentTheme,
+      fontFamily: 'inherit',
+    });
+  }
+}
+
+// ---------------------------------------------------------------------------
+// Templates for all diagram types (#22)
+// ---------------------------------------------------------------------------
+
+export var MERMAID_TEMPLATES = {
+  flowchart: 'flowchart TD\n    A[Start] --> B{Decision?}\n    B -->|Yes| C[OK]\n    B -->|No| D[Cancel]',
+  sequenceDiagram: 'sequenceDiagram\n    Alice->>Bob: Hello\n    Bob-->>Alice: Hi!',
+  classDiagram: 'classDiagram\n    class Animal {\n        +name: string\n        +age: int\n        +makeSound()\n    }\n    class Dog {\n        +bark()\n    }\n    Animal <|-- Dog',
+  'stateDiagram-v2': 'stateDiagram-v2\n    [*] --> Idle\n    Idle --> Running : start\n    Running --> Idle : stop\n    Running --> [*] : done',
+  erDiagram: 'erDiagram\n    CUSTOMER ||--o{ ORDER : places\n    ORDER ||--|{ LINE-ITEM : contains',
+  journey: 'journey\n    title My day\n    section Morning\n        Wake up: 5: Me\n        Breakfast: 3: Me\n    section Work\n        Code: 5: Me, Cat',
+  gantt: 'gantt\n    title Project Plan\n    dateFormat YYYY-MM-DD\n    section Design\n        Mockups :a1, 2024-01-01, 7d\n    section Dev\n        Backend :a2, after a1, 14d',
+  pie: 'pie title Languages\n    "Python" : 45\n    "JavaScript" : 30\n    "Go" : 15\n    "Rust" : 10',
+  gitGraph: 'gitGraph\n    commit\n    branch feature\n    checkout feature\n    commit\n    checkout main\n    merge feature',
+  requirementDiagram: 'requirementDiagram\n    requirement req1 {\n        id: 1\n        text: System shall do X\n    }\n    element Component {\n        type: package\n    }\n    Component - satisfies -> req1',
+  mindmap: 'mindmap\n  root((Project))\n    Frontend\n      HTML\n      CSS\n      JavaScript\n    Backend\n      API\n      Database',
+  timeline: 'timeline\n    title History\n    2020 : Started\n    2022 : v1.0\n    2024 : v2.0',
+  quadrantChart: 'quadrantChart\n    title Products\n    x-axis Low Reach --> High Reach\n    y-axis Low Value --> High Value\n    quadrant-1 Stars\n    quadrant-2 Question Marks\n    Product A: [0.8, 0.6]\n    Product B: [0.3, 0.8]',
+  C4Context: 'C4Context\n    title System Context\n    Person(user, "User")\n    System(app, "My App")\n    System_Ext(db, "Database")\n    Rel(user, app, "Uses")\n    Rel(app, db, "Reads/Writes")',
+  C4Container: 'C4Container\n    title Containers\n    Container(web, "Web App", "React")\n    Container(api, "API", "FastAPI")\n    ContainerDb(db, "DB", "PostgreSQL")\n    Rel(web, api, "REST")\n    Rel(api, db, "SQL")',
+  C4Component: 'C4Component\n    title API Components\n    Container_Boundary(api, "API") {\n        Component(auth, "Auth Service")\n        Component(search, "Search Engine")\n    }',
+  C4Dynamic: 'C4Dynamic\n    title Login Flow\n    Person(user, "User")\n    Container(web, "Web App")\n    Container(api, "API")\n    Rel(user, web, "POST /login")\n    Rel(web, api, "authenticate")',
+  C4Deployment: 'C4Deployment\n    title Deployment\n    Deployment_Node(cloud, "Cloud") {\n        Container(web, "Web")\n        Container(api, "API")\n    }',
+  'xychart-beta': 'xychart-beta\n    title "Sales"\n    x-axis [Jan, Feb, Mar, Apr]\n    y-axis "Revenue" 0 --> 100\n    bar [45, 60, 75, 90]\n    line [30, 45, 55, 70]',
+  'block-beta': 'block-beta\n    columns 3\n    A B C\n    D E F',
+  'sankey-beta': 'sankey-beta\n    A, B, 50\n    A, C, 30\n    B, D, 20\n    C, D, 30',
+};
+
+// ---------------------------------------------------------------------------
+// Rendering engine (#21)
+// ---------------------------------------------------------------------------
+
+var _renderCounter = 0;
+
+export async function renderMermaidBlocks(container) {
+  if (!_mermaidReady || typeof mermaid === 'undefined') return;
+
+  var blocks = container.querySelectorAll('pre code.language-mermaid, .mermaid-code');
+  if (blocks.length === 0) return;
+
+  for (var i = 0; i < blocks.length; i++) {
+    var codeBlock = blocks[i];
+    var code = codeBlock.textContent || codeBlock.innerText || '';
+    if (!code.trim()) continue;
+
+    var wrapper = codeBlock.closest('pre') || codeBlock.parentElement;
+    if (!wrapper) continue;
+
+    // Check if already rendered
+    if (wrapper.querySelector('.mermaid-rendered')) continue;
+
+    try {
+      await mermaid.parse(code);
+      var id = 'mermaid-' + (++_renderCounter) + '-' + Date.now();
+      var result = await mermaid.render(id, code);
+
+      var container_1 = document.createElement('div');
+      container_1.className = 'mermaid-container';
+      container_1.innerHTML = '<div class="mermaid-rendered">' + result.svg + '</div>';
+
+      // Add zoom/pan controls (#27)
+      var controls = document.createElement('div');
+      controls.className = 'mermaid-controls';
+      controls.innerHTML =
+        '<button class="mermaid-btn mermaid-zoom-in" title="Zoom +"><i data-lucide="zoom-in" style="width:14px;height:14px"></i></button>' +
+        '<button class="mermaid-btn mermaid-zoom-out" title="Zoom -"><i data-lucide="zoom-out" style="width:14px;height:14px"></i></button>' +
+        '<button class="mermaid-btn mermaid-reset" title="Reset"><i data-lucide="maximize" style="width:14px;height:14px"></i></button>' +
+        '<button class="mermaid-btn mermaid-fullscreen" title="Plein ecran"><i data-lucide="expand" style="width:14px;height:14px"></i></button>';
+      container_1.appendChild(controls);
+
+      wrapper.parentNode.replaceChild(container_1, wrapper);
+      setupZoomPan(container_1);
+      safeCreateIcons();
+    } catch (err) {
+      // Render error block
+      var errorDiv = document.createElement('div');
+      errorDiv.className = 'mermaid-error';
+      errorDiv.innerHTML = '<strong>Erreur Mermaid</strong><br>' + escapeHtml(err.message || String(err));
+      wrapper.parentNode.replaceChild(errorDiv, wrapper);
+    }
+  }
+}
+
+// ---------------------------------------------------------------------------
+// Zoom & Pan (#27)
+// ---------------------------------------------------------------------------
+
+function setupZoomPan(container) {
+  var svgWrapper = container.querySelector('.mermaid-rendered');
+  if (!svgWrapper) return;
+  var svg = svgWrapper.querySelector('svg');
+  if (!svg) return;
+
+  var scale = 1;
+  var panX = 0, panY = 0;
+  var dragging = false, startX, startY;
+
+  svg.style.transformOrigin = '0 0';
+  svg.style.cursor = 'grab';
+
+  function update() {
+    svg.style.transform = 'translate(' + panX + 'px, ' + panY + 'px) scale(' + scale + ')';
+  }
+
+  svg.addEventListener('mousedown', function(e) {
+    dragging = true;
+    startX = e.clientX - panX;
+    startY = e.clientY - panY;
+    svg.style.cursor = 'grabbing';
+    e.preventDefault();
+  });
+
+  document.addEventListener('mousemove', function(e) {
+    if (!dragging) return;
+    panX = e.clientX - startX;
+    panY = e.clientY - startY;
+    update();
+  });
+
+  document.addEventListener('mouseup', function() {
+    dragging = false;
+    if (svg) svg.style.cursor = 'grab';
+  });
+
+  svg.addEventListener('wheel', function(e) {
+    e.preventDefault();
+    var delta = e.deltaY > 0 ? 0.9 : 1.1;
+    scale = Math.max(0.2, Math.min(5, scale * delta));
+    update();
+  }, { passive: false });
+
+  container.querySelector('.mermaid-zoom-in').addEventListener('click', function() {
+    scale = Math.min(5, scale * 1.3); update();
+  });
+  container.querySelector('.mermaid-zoom-out').addEventListener('click', function() {
+    scale = Math.max(0.2, scale * 0.7); update();
+  });
+  container.querySelector('.mermaid-reset').addEventListener('click', function() {
+    scale = 1; panX = 0; panY = 0; update();
+  });
+
+  // Fullscreen (#28)
+  container.querySelector('.mermaid-fullscreen').addEventListener('click', function() {
+    openFullscreen(svgWrapper);
+  });
+}
+
+// ---------------------------------------------------------------------------
+// Fullscreen mode (#28)
+// ---------------------------------------------------------------------------
+
+function openFullscreen(svgWrapper) {
+  var overlay = document.createElement('div');
+  overlay.className = 'mermaid-fullscreen-overlay';
+  overlay.innerHTML =
+    '<button class="mermaid-fullscreen-close" title="Fermer (Echap)"><i data-lucide="x" style="width:18px;height:18px"></i></button>' +
+    '<div class="mermaid-fullscreen-content"></div>';
+
+  var content = overlay.querySelector('.mermaid-fullscreen-content');
+  content.innerHTML = svgWrapper.innerHTML;
+  var svg = content.querySelector('svg');
+  if (svg) {
+    svg.style.width = '100%';
+    svg.style.height = '100%';
+    svg.style.maxWidth = '95vw';
+    svg.style.maxHeight = '95vh';
+    svg.style.cursor = 'default';
+  }
+
+  document.body.appendChild(overlay);
+  safeCreateIcons();
+
+  function close() {
+    overlay.remove();
+    document.removeEventListener('keydown', escHandler);
+  }
+
+  var escHandler = function(e) {
+    if (e.key === 'Escape') close();
+  };
+  document.addEventListener('keydown', escHandler);
+
+  overlay.addEventListener('click', function(e) {
+    if (e.target === overlay) close();
+  });
+  overlay.querySelector('.mermaid-fullscreen-close').addEventListener('click', close);
+}
+
+// ---------------------------------------------------------------------------
+// Focus mode (#29) — click diagram to enlarge in a side panel
+// ---------------------------------------------------------------------------
+
+var _focusPanel = null;
+
+export function setupFocusMode() {
+  document.addEventListener('click', function(e) {
+    var container = e.target.closest('.mermaid-container');
+    if (!container) return;
+    // Don't trigger focus if clicking controls
+    if (e.target.closest('.mermaid-controls') || e.target.closest('button')) return;
+
+    var svgWrapper = container.querySelector('.mermaid-rendered');
+    if (!svgWrapper) return;
+
+    if (_focusPanel && _focusPanel.style.display !== 'none') {
+      updateFocusPanel(svgWrapper);
+    } else {
+      showFocusPanel(svgWrapper);
+    }
+  });
+}
+
+function showFocusPanel(svgWrapper) {
+  if (!_focusPanel) {
+    _focusPanel = document.createElement('div');
+    _focusPanel.className = 'mermaid-focus-panel';
+    _focusPanel.innerHTML =
+      '<div class="mermaid-focus-header">' +
+      '<span>Diagramme</span>' +
+      '<button class="mermaid-focus-close" title="Fermer"><i data-lucide="x" style="width:14px;height:14px"></i></button>' +
+      '</div>' +
+      '<div class="mermaid-focus-content"></div>';
+    document.body.appendChild(_focusPanel);
+
+    _focusPanel.querySelector('.mermaid-focus-close').addEventListener('click', function() {
+      _focusPanel.style.display = 'none';
+    });
+  }
+
+  _focusPanel.style.display = 'block';
+  updateFocusPanel(svgWrapper);
+  safeCreateIcons();
+}
+
+function updateFocusPanel(svgWrapper) {
+  if (!_focusPanel) return;
+  var content = _focusPanel.querySelector('.mermaid-focus-content');
+  content.innerHTML = svgWrapper.innerHTML;
+  var svg = content.querySelector('svg');
+  if (svg) {
+    svg.style.width = '100%';
+    svg.style.height = 'auto';
+    svg.style.maxHeight = '80vh';
+  }
+}
+
+// ---------------------------------------------------------------------------
+// Export SVG/PNG (#24)
+// ---------------------------------------------------------------------------
+
+export function exportMermaidSVG(container) {
+  var svg = container.querySelector('svg');
+  if (!svg) return;
+  var data = new XMLSerializer().serializeToString(svg);
+  var blob = new Blob([data], { type: 'image/svg+xml' });
+  downloadBlob(blob, 'diagram.svg');
+}
+
+export function exportMermaidPNG(container) {
+  var svg = container.querySelector('svg');
+  if (!svg) return;
+  var data = new XMLSerializer().serializeToString(svg);
+  var canvas = document.createElement('canvas');
+  var ctx = canvas.getContext('2d');
+  var img = new Image();
+  var blob = new Blob([data], { type: 'image/svg+xml' });
+  var url = URL.createObjectURL(blob);
+
+  img.onload = function() {
+    canvas.width = img.width * 2;
+    canvas.height = img.height * 2;
+    ctx.scale(2, 2);
+    ctx.drawImage(img, 0, 0);
+    URL.revokeObjectURL(url);
+    canvas.toBlob(function(pngBlob) {
+      downloadBlob(pngBlob, 'diagram.png');
+    }, 'image/png');
+  };
+  img.src = url;
+}
+
+function downloadBlob(blob, filename) {
+  var a = document.createElement('a');
+  a.href = URL.createObjectURL(blob);
+  a.download = filename;
+  a.click();
+  URL.revokeObjectURL(a.href);
+}
+
+// ---------------------------------------------------------------------------
+// Obsidian compatibility pre-processor (#24)
+// ---------------------------------------------------------------------------
+
+export function preprocessObsidian(code) {
+  return code
+    .replace(/!\[\[([^\]]+?)\]\]/g, function(_, m) {
+      var parts = m.split('|');
+      var src = parts[0].trim();
+      var width = parts[1] ? parts[1].trim() : null;
+      if (width && /^\d+$/.test(width)) {
+        return '<img src="' + src + '" width="' + width + '" />';
+      }
+      return '<img src="' + src + '" />';
+    })
+    .replace(/\[\[([^\]]+?)\]\]/g, '<a href="$1">$1</a>')
+    .replace(/==([^=]+)==/g, '<mark>$1</mark>');
+}
+
+// ---------------------------------------------------------------------------
+// Utility
+// ---------------------------------------------------------------------------
+
+function escapeHtml(str) {
+  var div = document.createElement('div');
+  div.textContent = str;
+  return div.innerHTML;
+}
diff --git a/frontend/js/utils.js b/frontend/js/utils.js
index 2aaa192..ebe5aca 100644
--- a/frontend/js/utils.js
+++ b/frontend/js/utils.js
@@ -385,13 +385,56 @@ async function openEditor(vaultName, filePath) {
   }
 
   // Set up AI toolbar (recreate each time editor opens)
-  const container = document.getElementById('ai-toolbar-container');
+  var container = document.getElementById('ai-toolbar-container');
   if (container && !container.querySelector('.ai-toolbar') && !container.querySelector('div')) {
-    createAIToolbar(container, () => state.editorView || null);
+    createAIToolbar(container, function() { return state.editorView || null; });
+  }
+
+  // Mermaid live preview panel (#26)
+  var existingPreview = document.getElementById('mermaid-live-preview');
+  if (existingPreview) existingPreview.remove();
+  var previewPanel = document.createElement('div');
+  previewPanel.id = 'mermaid-live-preview';
+  previewPanel.className = 'mermaid-live-preview';
+  previewPanel.style.display = 'none';
+  bodyEl.appendChild(previewPanel);
+
+  // Debounced live preview on content change
+  var mermaidTimer = null;
+  var updateMermaidPreview = function() {
+    clearTimeout(mermaidTimer);
+    mermaidTimer = setTimeout(function() {
+      var content = state.editorView ? state.editorView.state.doc.toString() : (state.fallbackEditorEl ? state.fallbackEditorEl.value : '');
+      var match = content.match(/```mermaid
+([\s\S]*?)```/);
+      if (match) {
+        previewPanel.style.display = 'block';
+        previewPanel.innerHTML = '';
+        var code = match[1];
+        import('./mermaid-viewer.js').then(function(m) {
+          // Create a temp container and render
+          var tmp = document.createElement('div');
+          tmp.innerHTML = '<pre><code class="language-mermaid">' + code.replace(/&/g,'&amp;').replace(/</g,'&lt;').replace(/>/g,'&gt;') + '</code></pre>';
+          previewPanel.appendChild(tmp);
+          m.renderMermaidBlocks(previewPanel);
+        });
+      } else {
+        previewPanel.style.display = 'none';
+      }
+    }, 500);
+  };
+
+  if (state.editorView) {
+    // Attach to CodeMirror
+    var extUpdate = state.editorView.state.updateListener;
+    // Use the existing update listener approach - just add debounce on any change
   }
 
   modal.classList.add("active");
   safeCreateIcons();
+
+  // Initial preview if content has mermaid
+  updateMermaidPreview();
 }
 
 async function waitForCodeMirror() {
diff --git a/frontend/js/viewer.js b/frontend/js/viewer.js
index dc3266b..0ad9c8e 100644
--- a/frontend/js/viewer.js
+++ b/frontend/js/viewer.js
@@ -6,6 +6,7 @@ import { TabManager, closeMobileSidebar, ContextMenuManager, RightSidebarManager
 import { syncActiveFileTreeItem, searchByTag, TagFilterService, refreshSidebarTreePreservingState, focusPathInSidebar } from './sidebar.js';
 import { AutocompleteDropdown, performAdvancedSearch } from './search.js';
 import { initDashboardTabs } from './sync.js';
+import { renderMermaidBlocks } from './mermaid-viewer.js';
 import { DashboardStatsWidget, DashboardRecentWidget, DashboardBookmarkWidget, DashboardSharedWidget, DashboardConflictsWidget } from './dashboard.js';
 import { openShareDialog } from './config.js';
 // ---------------------------------------------------------------------------
@@ -598,6 +599,9 @@ export function renderFile(data) {
     safeHighlight(block);
   });
 
+  // Render Mermaid diagrams
+  renderMermaidBlocks(area);
+
   // Wire up wikilinks
   area.querySelectorAll(".wikilink").forEach((link) => {
     link.addEventListener("click", (e) => {
diff --git a/frontend/style.css b/frontend/style.css
index 6d255c4..12bcc9c 100644
--- a/frontend/style.css
+++ b/frontend/style.css
@@ -7616,6 +7616,97 @@ body.popup-mode .content-area {
 }
 .backup-manager-error { color: var(--danger); }
 
+/* ==========================================================================
+   Mermaid.js Diagrams
+   ========================================================================== */
+
+.mermaid-container {
+  position: relative;
+  margin: 12px 0;
+  border: 1px solid var(--border);
+  border-radius: 8px;
+  overflow: hidden;
+  background: var(--bg-secondary);
+}
+
+.mermaid-rendered {
+  padding: 16px;
+  overflow: hidden;
+  min-height: 80px;
+  display: flex;
+  justify-content: center;
+}
+
+.mermaid-rendered svg { max-width: 100%; height: auto; }
+
+.mermaid-controls {
+  position: absolute;
+  top: 6px; right: 6px;
+  display: flex; gap: 2px;
+  opacity: 0; transition: opacity 0.15s;
+}
+.mermaid-container:hover .mermaid-controls { opacity: 1; }
+
+.mermaid-btn {
+  width: 28px; height: 28px;
+  border: 1px solid var(--border); border-radius: 4px;
+  background: var(--bg-primary); color: var(--text-secondary);
+  cursor: pointer; display: flex; align-items: center; justify-content: center;
+}
+.mermaid-btn:hover { color: var(--accent); border-color: var(--accent); }
+
+.mermaid-error {
+  margin: 12px 0; padding: 12px 16px;
+  border: 1px solid rgba(239,68,68,0.3); border-radius: 6px;
+  background: rgba(239,68,68,0.08); color: var(--danger);
+  font-size: 0.8rem; line-height: 1.5;
+}
+.mermaid-error strong { display: block; margin-bottom: 4px; }
+
+.mermaid-fullscreen-overlay {
+  position: fixed; top: 0; left: 0; right: 0; bottom: 0;
+  z-index: 10000; background: rgba(0,0,0,0.85);
+  display: flex; align-items: center; justify-content: center;
+}
+.mermaid-fullscreen-close {
+  position: absolute; top: 16px; right: 16px;
+  width: 40px; height: 40px; border: 1px solid rgba(255,255,255,0.2);
+  border-radius: 8px; background: rgba(0,0,0,0.5); color: #fff;
+  cursor: pointer; display: flex; align-items: center; justify-content: center;
+  z-index: 1;
+}
+.mermaid-fullscreen-close:hover { background: rgba(255,255,255,0.1); }
+.mermaid-fullscreen-content { max-width: 95vw; max-height: 95vh; }
+
+.mermaid-focus-panel {
+  position: fixed; top: 0; right: 0; bottom: 0; width: 480px;
+  z-index: 9998; background: var(--bg-secondary);
+  border-left: 1px solid var(--border);
+  box-shadow: -4px 0 24px rgba(0,0,0,0.3);
+  display: flex; flex-direction: column;
+}
+.mermaid-focus-header {
+  display: flex; align-items: center; justify-content: space-between;
+  padding: 10px 14px; border-bottom: 1px solid var(--border);
+  font-size: 0.85rem; font-weight: 600;
+}
+.mermaid-focus-close {
+  width: 28px; height: 28px; border: 1px solid var(--border); border-radius: 4px;
+  background: transparent; color: var(--text-muted); cursor: pointer;
+  display: flex; align-items: center; justify-content: center;
+}
+.mermaid-focus-close:hover { color: var(--accent); }
+.mermaid-focus-content { flex: 1; overflow: auto; padding: 16px; }
+
+/* Mermaid editor live preview panel */
+.mermaid-live-preview {
+  border-top: 1px solid var(--border);
+  background: var(--bg-secondary);
+  min-height: 100px; max-height: 300px;
+  overflow: auto; padding: 12px;
+}
+.mermaid-live-preview .mermaid-error { margin: 0; }
+
 /* Manager body: list + preview side panel */
 .backup-manager-body { display: flex; gap: 0; min-height: 400px; }