diff --git a/apps/web/src/components/MermaidCodeBlock.tsx b/apps/web/src/components/MermaidCodeBlock.tsx
index db684990..f36c2df6 100644
--- a/apps/web/src/components/MermaidCodeBlock.tsx
+++ b/apps/web/src/components/MermaidCodeBlock.tsx
@@ -1,9 +1,10 @@
 import { useEffect, useState } from "react";
 import { NodeViewContent, NodeViewWrapper, type NodeViewProps } from "@tiptap/react";
 import { useTranslation } from "react-i18next";
-import { Check, CircleAlert, Code2, Copy, Maximize2, Workflow } from "lucide-react";
+import { Check, CircleAlert, Code2, Copy, Maximize2 } from "lucide-react";
 import { MERMAID_THEME_PALETTES, useMermaidTheme } from "./ThemeProvider";
 import { MermaidViewer } from "./MermaidViewer";
+import { Tooltip, TooltipContent, TooltipProvider, TooltipTrigger } from "@/components/ui/tooltip";
 import { copyTextToClipboard } from "@/lib/clipboard";
 import { renderMermaidWithFallback } from "@/lib/mermaid-renderer";
 import { getOfficialMermaidThemeVariables } from "@/lib/mermaid-theme";
@@ -34,7 +35,7 @@ const loadBeautifulMermaid = () => {
 
 export const MermaidCodeBlock = ({ editor, node }: NodeViewProps) => {
   const { t } = useTranslation();
-  const { mermaidRenderer, mermaidTheme, setMermaidRenderer } = useMermaidTheme();
+  const { mermaidTheme } = useMermaidTheme();
   const language = typeof node.attrs.language === "string" ? node.attrs.language.toLowerCase() : "plaintext";
   const source = node.textContent.trim();
   const isMermaid = language === "mermaid";
@@ -90,7 +91,6 @@ export const MermaidCodeBlock = ({ editor, node }: NodeViewProps) => {
         return renderedSvg;
       });
       const renderPromise = renderMermaidWithFallback({
-        renderer: mermaidRenderer,
         renderBeautiful,
         renderOfficial,
       });
@@ -114,7 +114,7 @@ export const MermaidCodeBlock = ({ editor, node }: NodeViewProps) => {
       cancelled = true;
       window.clearTimeout(timer);
     };
-  }, [isMermaid, mermaidRenderer, mermaidTheme, source]);
+  }, [isMermaid, mermaidTheme, source]);
 
   return (
     <NodeViewWrapper
@@ -124,99 +124,106 @@ export const MermaidCodeBlock = ({ editor, node }: NodeViewProps) => {
       data-language={language}
     >
       {isMermaid ? (
-        <div className="edgeever-mermaid-toolbar" contentEditable={false}>
-          <button
-            type="button"
-            className="edgeever-mermaid-tool-button"
-            aria-label={t(mermaidRenderer === "mermaid"
-              ? "editorToolbar.mermaidUseOrthogonalLayout"
-              : "editorToolbar.mermaidUseStandardLayout")}
-            title={t(mermaidRenderer === "mermaid"
-              ? "editorToolbar.mermaidUseOrthogonalLayout"
-              : "editorToolbar.mermaidUseStandardLayout")}
-            aria-pressed={mermaidRenderer === "beautiful"}
-            onClick={(event) => {
-              event.preventDefault();
-              event.stopPropagation();
-              setMermaidRenderer(mermaidRenderer === "mermaid" ? "beautiful" : "mermaid");
-            }}
-            onMouseDown={(event) => event.preventDefault()}
-          >
-            <Workflow aria-hidden="true" />
-          </button>
-          <button
-            type="button"
-            className="edgeever-mermaid-tool-button"
-            data-state={copyState}
-            aria-label={t(copyState === "copied" ? "editorToolbar.codeCopied" : copyState === "error" ? "editorToolbar.codeCopyFailed" : "editorToolbar.copyCode")}
-            title={t(copyState === "copied" ? "editorToolbar.codeCopied" : copyState === "error" ? "editorToolbar.codeCopyFailed" : "editorToolbar.copyCode")}
-            onClick={(event) => {
-              event.preventDefault();
-              event.stopPropagation();
-              void handleCopy();
-            }}
-            onMouseDown={(event) => event.preventDefault()}
-          >
-            {copyState === "copied"
-              ? <Check aria-hidden="true" />
-              : copyState === "error"
-                ? <CircleAlert aria-hidden="true" />
-                : <Copy aria-hidden="true" />}
-          </button>
-          {editor.isEditable && (
-            <button
-              type="button"
-              className="edgeever-mermaid-tool-button"
-              aria-label={t(sourceVisible ? "editorToolbar.mermaidHideSource" : "editorToolbar.mermaidShowSource")}
-              title={t(sourceVisible ? "editorToolbar.mermaidHideSource" : "editorToolbar.mermaidShowSource")}
-              aria-pressed={sourceVisible}
-              onClick={(event) => {
-                event.preventDefault();
-                event.stopPropagation();
-                setSourceVisible((visible) => !visible);
-              }}
-              onMouseDown={(event) => event.preventDefault()}
-            >
-              <Code2 aria-hidden="true" />
-            </button>
-          )}
-          {svg && (
-            <button
-              type="button"
-              className="edgeever-mermaid-tool-button"
-              aria-label={t("editorToolbar.mermaidOpenViewer")}
-              title={t("editorToolbar.mermaidOpenViewer")}
-              onClick={(event) => {
-                event.preventDefault();
-                event.stopPropagation();
-                setViewerOpen(true);
-              }}
-              onMouseDown={(event) => event.preventDefault()}
-            >
-              <Maximize2 aria-hidden="true" />
-            </button>
-          )}
-        </div>
+        <TooltipProvider delayDuration={0} skipDelayDuration={0}>
+          <div className="edgeever-mermaid-toolbar" contentEditable={false}>
+            <Tooltip>
+              <TooltipTrigger asChild>
+                <button
+                  type="button"
+                  className="edgeever-mermaid-tool-button"
+                  data-state={copyState}
+                  aria-label={t(copyState === "copied" ? "editorToolbar.codeCopied" : copyState === "error" ? "editorToolbar.codeCopyFailed" : "editorToolbar.copyCode")}
+                  onClick={(event) => {
+                    event.preventDefault();
+                    event.stopPropagation();
+                    void handleCopy();
+                  }}
+                  onMouseDown={(event) => event.preventDefault()}
+                >
+                  {copyState === "copied"
+                    ? <Check aria-hidden="true" />
+                    : copyState === "error"
+                      ? <CircleAlert aria-hidden="true" />
+                      : <Copy aria-hidden="true" />}
+                </button>
+              </TooltipTrigger>
+              <TooltipContent side="bottom">
+                {t(copyState === "copied" ? "editorToolbar.codeCopied" : copyState === "error" ? "editorToolbar.codeCopyFailed" : "editorToolbar.copyCode")}
+              </TooltipContent>
+            </Tooltip>
+            {editor.isEditable && (
+              <Tooltip>
+                <TooltipTrigger asChild>
+                  <button
+                    type="button"
+                    className="edgeever-mermaid-tool-button"
+                    aria-label={t(sourceVisible ? "editorToolbar.mermaidHideSource" : "editorToolbar.mermaidShowSource")}
+                    aria-pressed={sourceVisible}
+                    onClick={(event) => {
+                      event.preventDefault();
+                      event.stopPropagation();
+                      setSourceVisible((visible) => !visible);
+                    }}
+                    onMouseDown={(event) => event.preventDefault()}
+                  >
+                    <Code2 aria-hidden="true" />
+                  </button>
+                </TooltipTrigger>
+                <TooltipContent side="bottom">
+                  {t(sourceVisible ? "editorToolbar.mermaidHideSource" : "editorToolbar.mermaidShowSource")}
+                </TooltipContent>
+              </Tooltip>
+            )}
+            {svg && (
+              <Tooltip>
+                <TooltipTrigger asChild>
+                  <button
+                    type="button"
+                    className="edgeever-mermaid-tool-button"
+                    aria-label={t("editorToolbar.mermaidOpenViewer")}
+                    onClick={(event) => {
+                      event.preventDefault();
+                      event.stopPropagation();
+                      setViewerOpen(true);
+                    }}
+                    onMouseDown={(event) => event.preventDefault()}
+                  >
+                    <Maximize2 aria-hidden="true" />
+                  </button>
+                </TooltipTrigger>
+                <TooltipContent side="bottom">{t("editorToolbar.mermaidOpenViewer")}</TooltipContent>
+              </Tooltip>
+            )}
+          </div>
+        </TooltipProvider>
       ) : (
-        <button
-          type="button"
-          className="edgeever-code-copy-button"
-          contentEditable={false}
-          aria-label={t(copyState === "copied" ? "editorToolbar.codeCopied" : copyState === "error" ? "editorToolbar.codeCopyFailed" : "editorToolbar.copyCode")}
-          title={t(copyState === "copied" ? "editorToolbar.codeCopied" : copyState === "error" ? "editorToolbar.codeCopyFailed" : "editorToolbar.copyCode")}
-          onClick={(event) => {
-            event.preventDefault();
-            event.stopPropagation();
-            void handleCopy();
-          }}
-          onMouseDown={(event) => event.preventDefault()}
-        >
-          {copyState === "copied"
-            ? t("editorToolbar.codeCopied")
-            : copyState === "error"
-              ? t("editorToolbar.codeCopyFailed")
-              : t("editorToolbar.copyCode")}
-        </button>
+        <TooltipProvider delayDuration={0} skipDelayDuration={0}>
+          <Tooltip>
+            <TooltipTrigger asChild>
+              <button
+                type="button"
+                className="edgeever-code-copy-button"
+                contentEditable={false}
+                aria-label={t(copyState === "copied" ? "editorToolbar.codeCopied" : copyState === "error" ? "editorToolbar.codeCopyFailed" : "editorToolbar.copyCode")}
+                onClick={(event) => {
+                  event.preventDefault();
+                  event.stopPropagation();
+                  void handleCopy();
+                }}
+                onMouseDown={(event) => event.preventDefault()}
+              >
+                {copyState === "copied"
+                  ? t("editorToolbar.codeCopied")
+                  : copyState === "error"
+                    ? t("editorToolbar.codeCopyFailed")
+                    : t("editorToolbar.copyCode")}
+              </button>
+            </TooltipTrigger>
+            <TooltipContent side="bottom">
+              {t(copyState === "copied" ? "editorToolbar.codeCopied" : copyState === "error" ? "editorToolbar.codeCopyFailed" : "editorToolbar.copyCode")}
+            </TooltipContent>
+          </Tooltip>
+        </TooltipProvider>
       )}
       {isMermaid && (
         <div
diff --git a/apps/web/src/components/MermaidViewer.tsx b/apps/web/src/components/MermaidViewer.tsx
index 0642ec02..aa45558e 100644
--- a/apps/web/src/components/MermaidViewer.tsx
+++ b/apps/web/src/components/MermaidViewer.tsx
@@ -8,6 +8,7 @@ import {
   normalizeMermaidSvgForViewer,
   resolveMermaidViewerBackground,
 } from "@/lib/mermaid-svg";
+import { Tooltip, TooltipContent, TooltipProvider, TooltipTrigger } from "@/components/ui/tooltip";
 
 interface MermaidViewerProps {
   closeLabel: string;
@@ -60,17 +61,22 @@ export const MermaidViewer = ({
   if (!open || !objectUrl) return null;
 
   const resetButton = (
-    <button
-      key="reset-mermaid-zoom"
-      type="button"
-      className="edgeever-mermaid-viewer-reset"
-      disabled={zoom <= 1}
-      aria-label={resetZoomLabel}
-      title={resetZoomLabel}
-      onClick={() => zoomRef.current?.changeZoom(1)}
-    >
-      <RotateCcw aria-hidden="true" />
-    </button>
+    <TooltipProvider key="reset-mermaid-zoom" delayDuration={0} skipDelayDuration={0}>
+      <Tooltip>
+        <TooltipTrigger asChild>
+          <button
+            type="button"
+            className="edgeever-mermaid-viewer-reset"
+            disabled={zoom <= 1}
+            aria-label={resetZoomLabel}
+            onClick={() => zoomRef.current?.changeZoom(1)}
+          >
+            <RotateCcw aria-hidden="true" />
+          </button>
+        </TooltipTrigger>
+        <TooltipContent side="bottom">{resetZoomLabel}</TooltipContent>
+      </Tooltip>
+    </TooltipProvider>
   );
 
   return (
diff --git a/apps/web/src/components/ThemeProvider.tsx b/apps/web/src/components/ThemeProvider.tsx
index 034c1fa5..f32bed94 100644
--- a/apps/web/src/components/ThemeProvider.tsx
+++ b/apps/web/src/components/ThemeProvider.tsx
@@ -49,9 +49,6 @@ export const MERMAID_THEME_PALETTES: Record<MermaidThemeName, MermaidThemePalett
   "one-dark": { bg: "#282c34", fg: "#abb2bf", line: "#4b5263", accent: "#c678dd", muted: "#5c6370" },
 };
 
-export const MERMAID_RENDERERS = ["mermaid", "beautiful"] as const;
-export type MermaidRenderer = (typeof MERMAID_RENDERERS)[number];
-
 export const EDITOR_THEME_NAMES = [
   "default",
   "minimal-emerald",
@@ -117,8 +114,6 @@ interface AppearanceThemeContextValue {
 interface MermaidThemeContextValue {
   mermaidTheme: MermaidThemeName;
   setMermaidTheme: (theme: MermaidThemeName) => void;
-  mermaidRenderer: MermaidRenderer;
-  setMermaidRenderer: (renderer: MermaidRenderer) => void;
 }
 
 interface EditorThemeContextValue {
@@ -136,7 +131,6 @@ interface ThemeProviderProps {
 
 const THEME_STORAGE_KEY = "edgeever.theme";
 const MERMAID_THEME_STORAGE_KEY = "edgeever.mermaid-theme";
-const MERMAID_RENDERER_STORAGE_KEY = "edgeever.mermaid-renderer";
 const EDITOR_THEME_STORAGE_KEY = "edgeever.editor-theme";
 const CUSTOM_EDITOR_THEME_STORAGE_KEY = "edgeever.custom-editor-theme";
 const CUSTOM_EDITOR_THEMES_STORAGE_KEY = "edgeever.custom-editor-themes";
@@ -173,11 +167,6 @@ export const getStoredMermaidTheme = (): MermaidThemeName => {
   return MERMAID_THEME_NAMES.includes(stored as MermaidThemeName) ? stored as MermaidThemeName : "zinc-light";
 };
 
-export const getStoredMermaidRenderer = (): MermaidRenderer => {
-  const stored = readLocalStorageItem(MERMAID_RENDERER_STORAGE_KEY);
-  return MERMAID_RENDERERS.includes(stored as MermaidRenderer) ? stored as MermaidRenderer : "beautiful";
-};
-
 export const getStoredEditorTheme = (): string => {
   return readLocalStorageItem(EDITOR_THEME_STORAGE_KEY) || "default";
 };
@@ -267,7 +256,6 @@ export const ThemeProvider = ({ children }: ThemeProviderProps) => {
   const [preference, setPreferenceState] = useState<ThemePreference>(getStoredThemePreference);
   const [resolvedTheme, setResolvedTheme] = useState<ResolvedTheme>(() => resolveTheme(preference));
   const [mermaidTheme, setMermaidThemeState] = useState<MermaidThemeName>(getStoredMermaidTheme);
-  const [mermaidRenderer, setMermaidRendererState] = useState<MermaidRenderer>(getStoredMermaidRenderer);
   const [editorTheme, setEditorThemeState] = useState<string>(getStoredEditorTheme);
   const [customEditorThemes, setCustomEditorThemesState] = useState<CustomEditorTheme[]>(getStoredCustomEditorThemes);
 
@@ -323,11 +311,6 @@ export const ThemeProvider = ({ children }: ThemeProviderProps) => {
     window.localStorage.setItem(MERMAID_THEME_STORAGE_KEY, nextTheme);
   }, []);
 
-  const setMermaidRenderer = useCallback((nextRenderer: MermaidRenderer) => {
-    setMermaidRendererState(nextRenderer);
-    window.localStorage.setItem(MERMAID_RENDERER_STORAGE_KEY, nextRenderer);
-  }, []);
-
   const setEditorTheme = useCallback((nextTheme: string) => {
     setEditorThemeState(nextTheme);
     window.localStorage.setItem(EDITOR_THEME_STORAGE_KEY, nextTheme);
@@ -346,10 +329,8 @@ export const ThemeProvider = ({ children }: ThemeProviderProps) => {
     () => ({
       mermaidTheme,
       setMermaidTheme,
-      mermaidRenderer,
-      setMermaidRenderer,
     }),
-    [mermaidRenderer, mermaidTheme, setMermaidRenderer, setMermaidTheme]
+    [mermaidTheme, setMermaidTheme]
   );
 
   const editorValue = useMemo(
diff --git a/apps/web/src/components/mermaid-tooltip.test.mjs b/apps/web/src/components/mermaid-tooltip.test.mjs
new file mode 100644
index 00000000..5a270260
--- /dev/null
+++ b/apps/web/src/components/mermaid-tooltip.test.mjs
@@ -0,0 +1,18 @@
+import { describe, expect, test } from "bun:test";
+import { readFileSync } from "node:fs";
+
+const readSource = (relativePath) => readFileSync(new URL(relativePath, import.meta.url), "utf8");
+
+describe("Mermaid tooltips", () => {
+  test("uses shared tooltips instead of native title attributes", () => {
+    const codeBlock = readSource("./MermaidCodeBlock.tsx");
+    const viewer = readSource("./MermaidViewer.tsx");
+
+    expect(codeBlock).toContain("TooltipProvider");
+    expect(codeBlock).toContain("TooltipTrigger");
+    expect(codeBlock).toContain("TooltipContent");
+    expect(viewer).toContain("TooltipContent");
+    expect(codeBlock).not.toMatch(/\btitle=/);
+    expect(viewer).not.toMatch(/\btitle=/);
+  });
+});
diff --git a/apps/web/src/lib/mermaid-renderer.test.mjs b/apps/web/src/lib/mermaid-renderer.test.mjs
index c0e3ed6e..fc3cd8c7 100644
--- a/apps/web/src/lib/mermaid-renderer.test.mjs
+++ b/apps/web/src/lib/mermaid-renderer.test.mjs
@@ -1,7 +1,6 @@
-import { afterEach, describe, expect, test } from "bun:test";
+import { describe, expect, test } from "bun:test";
 import { renderMermaidSVG } from "beautiful-mermaid";
 import mermaid from "mermaid";
-import { getStoredMermaidRenderer } from "../components/ThemeProvider";
 import { renderMermaidWithFallback } from "./mermaid-renderer";
 
 const GANTT_SOURCE = `gantt
@@ -9,49 +8,19 @@ const GANTT_SOURCE = `gantt
   section Web
   Compatibility fallback :fallback, 2026-07-30, 1d`;
 
-const originalWindow = Object.getOwnPropertyDescriptor(globalThis, "window");
-
-const restoreWindow = () => {
-  if (originalWindow) {
-    Object.defineProperty(globalThis, "window", originalWindow);
-  } else {
-    delete globalThis.window;
-  }
-};
-
-afterEach(() => {
-  restoreWindow();
-});
-
 describe("Mermaid renderer fallback", () => {
-  test("defaults to the compact renderer when no browser preference exists", () => {
-    delete globalThis.window;
-    expect(getStoredMermaidRenderer()).toBe("beautiful");
-  });
-
-  test("defaults to the compact renderer when window exists without localStorage", () => {
-    globalThis.window = {
-      location: { hostname: "notes.example.com" },
-    };
-    expect(getStoredMermaidRenderer()).toBe("beautiful");
-  });
-
-  test("defaults to the compact renderer when localStorage is empty or blocked", () => {
-    globalThis.window = {
-      localStorage: {
-        getItem: () => null,
+  test("always uses the compact renderer when it supports the diagram", async () => {
+    let officialRenderCount = 0;
+    const svg = await renderMermaidWithFallback({
+      renderBeautiful: () => '<svg data-renderer="beautiful"></svg>',
+      renderOfficial: () => {
+        officialRenderCount += 1;
+        return '<svg data-renderer="mermaid"></svg>';
       },
-    };
-    expect(getStoredMermaidRenderer()).toBe("beautiful");
+    });
 
-    globalThis.window = {
-      localStorage: {
-        getItem: () => {
-          throw new Error("blocked");
-        },
-      },
-    };
-    expect(getStoredMermaidRenderer()).toBe("beautiful");
+    expect(officialRenderCount).toBe(0);
+    expect(svg).toContain('data-renderer="beautiful"');
   });
 
   test("uses the official renderer for a valid Gantt diagram unsupported by beautiful-mermaid", async () => {
@@ -59,7 +28,6 @@ describe("Mermaid renderer fallback", () => {
 
     let officialRenderCount = 0;
     const svg = await renderMermaidWithFallback({
-      renderer: "beautiful",
       renderBeautiful: () => renderMermaidSVG(GANTT_SOURCE),
       renderOfficial: () => {
         officialRenderCount += 1;
diff --git a/apps/web/src/lib/mermaid-renderer.ts b/apps/web/src/lib/mermaid-renderer.ts
index cb1a3f4b..5bcc5617 100644
--- a/apps/web/src/lib/mermaid-renderer.ts
+++ b/apps/web/src/lib/mermaid-renderer.ts
@@ -1,23 +1,15 @@
-export type MermaidRendererName = "mermaid" | "beautiful";
-
 interface MermaidRenderFallbackOptions {
-  renderer: MermaidRendererName;
   renderBeautiful: () => string | Promise<string>;
   renderOfficial: () => string | Promise<string>;
 }
 
 export const renderMermaidWithFallback = async ({
-  renderer,
   renderBeautiful,
   renderOfficial,
 }: MermaidRenderFallbackOptions) => {
-  if (renderer === "beautiful") {
-    try {
-      return await renderBeautiful();
-    } catch {
-      return renderOfficial();
-    }
+  try {
+    return await renderBeautiful();
+  } catch {
+    return renderOfficial();
   }
-
-  return renderOfficial();
 };
diff --git a/packages/shared/src/i18n/en-US.ts b/packages/shared/src/i18n/en-US.ts
index 222c150e..6dc5cff3 100644
--- a/packages/shared/src/i18n/en-US.ts
+++ b/packages/shared/src/i18n/en-US.ts
@@ -1104,8 +1104,6 @@ export const enUS = {
     mermaidSource: "Mermaid source",
     mermaidShowSource: "Show Mermaid source",
     mermaidHideSource: "Hide Mermaid source",
-    mermaidUseStandardLayout: "Switch to standard layout",
-    mermaidUseOrthogonalLayout: "Switch to orthogonal layout",
     mermaidOpenViewer: "Open Mermaid diagram viewer",
     mermaidViewer: "Mermaid diagram viewer",
     mermaidZoomIn: "Zoom in diagram",
diff --git a/packages/shared/src/i18n/zh-CN.ts b/packages/shared/src/i18n/zh-CN.ts
index 6da9b831..5271ac92 100644
--- a/packages/shared/src/i18n/zh-CN.ts
+++ b/packages/shared/src/i18n/zh-CN.ts
@@ -1104,8 +1104,6 @@ export const zhCN = {
     mermaidSource: "Mermaid 源码",
     mermaidShowSource: "显示 Mermaid 源码",
     mermaidHideSource: "隐藏 Mermaid 源码",
-    mermaidUseStandardLayout: "切换到标准布局",
-    mermaidUseOrthogonalLayout: "切换到正交布局",
     mermaidOpenViewer: "放大查看 Mermaid 图表",
     mermaidViewer: "Mermaid 图表查看器",
     mermaidZoomIn: "放大图表",