diff --git a/input.css b/input.css
index 51865a5..42bcbef 100644
--- a/input.css
+++ b/input.css
@@ -663,6 +663,29 @@
     display: block;
   }
 
+  /* ── mermaid 图表容器 ──
+     data-mermaid-rendered 由 yggdrasil-core/mermaid.ts 渲染成功后标记在 <pre> 上。
+     渲染后 pre 唯一子元素是 <svg>（mermaid 块不注入 copy-code 按钮），flex 安全。
+     居中 + 缩放适配宽度，消除常规图的横向滚动；超宽图 overflow-x:auto 兜底。 */
+  .md-content pre[data-mermaid-rendered] {
+    display: flex;
+    justify-content: center;
+    align-items: center;
+    padding: 24px 16px;
+    overflow-x: auto;
+  }
+
+  .md-content pre[data-mermaid-rendered] > svg {
+    max-width: 100%;
+    height: auto;
+    display: block;
+  }
+
+  /* 渲染失败：保留原始源码，加 accent 色左边条提示（站点 accent 为绿，沿用配色体系） */
+  .md-content pre.mermaid-error {
+    border-left: 3px solid var(--color-paper-accent);
+  }
+
   .anchor {
     display: none;
     text-decoration: none;
diff --git a/libs/yggdrasil-core/src/mermaid.test.ts b/libs/yggdrasil-core/src/mermaid.test.ts
index 69c03ac..e99cb15 100644
--- a/libs/yggdrasil-core/src/mermaid.test.ts
+++ b/libs/yggdrasil-core/src/mermaid.test.ts
@@ -67,10 +67,46 @@ describe('initMermaid', () => {
     window.__initMermaid('.post-content', 'dark');
 
     await vi.waitFor(() => {
-      expect(mockInitialize).toHaveBeenCalledWith(expect.objectContaining({ theme: 'dark' }));
+      // base 主题 + darkMode 标志：让 themeVariables 完全控制 Catppuccin 调色板
+      expect(mockInitialize).toHaveBeenCalledWith(
+        expect.objectContaining({ theme: 'base', darkMode: true }),
+      );
     });
   });
 
+  it('亮/暗主题传入对应的 Catppuccin themeVariables', async () => {
+    // 暗色：Mocha 调色板（背景 #313244、文字 #cdd6f4）
+    const darkRoot = document.createElement('div');
+    darkRoot.className = 'post-content';
+    darkRoot.innerHTML = '<pre><code class="language-mermaid">graph TD; A--&gt;B</code></pre>';
+    document.body.appendChild(darkRoot);
+    window.__initMermaid('.post-content', 'dark');
+    await vi.waitFor(() => {
+      expect(mockInitialize).toHaveBeenCalled();
+    });
+    const darkCall = mockInitialize.mock.calls.slice(-1)[0]?.[0] as Record<string, unknown>;
+    const darkVars = darkCall.themeVariables as Record<string, string>;
+    expect(darkVars.background).toBe('#313244');
+    expect(darkVars.primaryTextColor).toBe('#cdd6f4');
+    expect(darkVars.lineColor).toBe('#a6adc8');
+
+    // 亮色：Latte 调色板（背景 #dce0e8、文字 #4c4f69）
+    document.body.innerHTML = '';
+    const lightRoot = document.createElement('div');
+    lightRoot.className = 'post-content';
+    lightRoot.innerHTML = '<pre><code class="language-mermaid">graph TD; A--&gt;B</code></pre>';
+    document.body.appendChild(lightRoot);
+    window.__initMermaid('.post-content', 'light');
+    await vi.waitFor(() => {
+      expect(mockInitialize).toHaveBeenCalled();
+    });
+    const lightCall = mockInitialize.mock.calls.slice(-1)[0]?.[0] as Record<string, unknown>;
+    const lightVars = lightCall.themeVariables as Record<string, string>;
+    expect(lightVars.background).toBe('#dce0e8');
+    expect(lightVars.primaryTextColor).toBe('#4c4f69');
+    expect(lightVars.lineColor).toBe('#5c5f77');
+  });
+
   it('幂等：重复调用不重复渲染已处理的块', async () => {
     const root = document.createElement('div');
     root.className = 'post-content';
@@ -137,7 +173,9 @@ describe('initMermaid', () => {
     await vi.waitFor(() => {
       expect(mockRender.mock.calls.length).toBeGreaterThan(firstRenderCalls);
     });
-    expect(mockInitialize).toHaveBeenLastCalledWith(expect.objectContaining({ theme: 'dark' }));
+    expect(mockInitialize).toHaveBeenLastCalledWith(
+      expect.objectContaining({ theme: 'base', darkMode: true }),
+    );
     expect(root.querySelector('pre')?.dataset.mermaidTheme).toBe('dark');
   });
 
diff --git a/libs/yggdrasil-core/src/mermaid.ts b/libs/yggdrasil-core/src/mermaid.ts
index b775e29..97dc59c 100644
--- a/libs/yggdrasil-core/src/mermaid.ts
+++ b/libs/yggdrasil-core/src/mermaid.ts
@@ -30,6 +30,127 @@ type MermaidApi = {
   render: (id: string, text: string) => Promise<{ svg: string }>;
 };
 
+/**
+ * Catppuccin themeVariables（与站点 --color-paper-* / .tmTheme 调色板对齐）。
+ *
+ * mermaid 把颜色烤进 SVG 内联 style，无法靠 CSS 原地改主题，故须在 initialize 时注入。
+ * 用 `theme: 'base'`（非 'default'/'dark'）：base 主题不硬编码颜色，themeVariables 能完全
+ * 控制调色板；'default' 主题硬编码 mainBkg=#ECECFF 等会阻断覆盖。
+ *
+ * 设计哲学：极简卡片化——节点用 surface 色阶（卡片感）、边框/连线用 subtext 色阶（克制）、
+ * 文字用 primary text。不滥用强调色，绿/紫等 accent 留给作者用 classDef 手动强调。
+ * hex 值取自 themes/Catppuccin Latte.tmTheme 与 Catppuccin Mocha.tmTheme。
+ *
+ * 覆盖的字段涵盖 flowchart / sequence / class 三类图（测试文章用到的全部类型）。
+ */
+
+/** Latte（亮）主题：节点 surface 色阶、文字 #4c4f69、连线 subtext1 #5c5f77。 */
+const LATTE_VARS = {
+  background: '#dce0e8', // = --color-paper-code-block，图背景与 pre 无缝衔接
+  // 节点填充：surface 色阶递进（主/次/三级），卡片质感
+  primaryColor: '#e6e9ef',
+  secondaryColor: '#ccd0da',
+  tertiaryColor: '#bcc0cc',
+  mainBkg: '#e6e9ef',
+  nodeBkg: '#e6e9ef',
+  secondBkg: '#ccd0da',
+  // 节点边框：surface1 偏冷灰
+  primaryBorderColor: '#bcc0cc',
+  secondaryBorderColor: '#acb0be',
+  tertiaryBorderColor: '#9ca0b0',
+  nodeBorder: '#bcc0cc',
+  clusterBorder: '#bcc0cc',
+  labelBoxBorderColor: '#bcc0cc',
+  // 文字：primary text #4c4f69
+  primaryTextColor: '#4c4f69',
+  secondaryTextColor: '#5c5f77',
+  tertiaryTextColor: '#6c6f85',
+  textColor: '#4c4f69',
+  nodeTextColor: '#4c4f69',
+  titleColor: '#4c4f69',
+  classText: '#4c4f69',
+  labelTextColor: '#4c4f69',
+  // 连线/箭头：subtext1 #5c5f77
+  lineColor: '#5c5f77',
+  defaultLinkColor: '#5c5f77',
+  arrowheadColor: '#5c5f77',
+  // 时序图
+  actorBkg: '#e6e9ef',
+  actorBorder: '#bcc0cc',
+  actorTextColor: '#4c4f69',
+  actorLineColor: '#5c5f77',
+  signalColor: '#5c5f77',
+  signalTextColor: '#4c4f69',
+  loopTextColor: '#4c4f69',
+  sequenceNumberColor: '#eff1f5',
+  activationBkgColor: '#ccd0da',
+  activationBorderColor: '#bcc0cc',
+  // 边标签 / 子图背景
+  edgeLabelBackground: '#eff1f5',
+  labelBoxBkgColor: '#eff1f5',
+  clusterBkg: 'rgba(239, 241, 245, 0.5)',
+  // 注释：低饱和黄（Latte yellow #df8e1d）
+  noteBkgColor: 'rgba(223, 142, 29, 0.15)',
+  noteBorderColor: '#df8e1d',
+  noteTextColor: '#4c4f69',
+  // 字体：与正文 sans 对齐，中文友好
+  fontFamily:
+    "-apple-system, BlinkMacSystemFont, 'Segoe UI', 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif",
+  fontSize: '16px',
+} as const;
+
+/** Mocha（暗）主题：节点 surface 色阶、文字 #cdd6f4、连线 subtext0 #a6adc8。 */
+const MOCHA_VARS = {
+  background: '#313244', // = --color-paper-code-block（暗）
+  primaryColor: '#45475a',
+  secondaryColor: '#585b70',
+  tertiaryColor: '#1e1e2e',
+  mainBkg: '#45475a',
+  nodeBkg: '#45475a',
+  secondBkg: '#585b70',
+  primaryBorderColor: '#585b70',
+  secondaryBorderColor: '#45475a',
+  tertiaryBorderColor: '#313244',
+  nodeBorder: '#585b70',
+  clusterBorder: '#585b70',
+  labelBoxBorderColor: '#585b70',
+  primaryTextColor: '#cdd6f4',
+  secondaryTextColor: '#bac2de',
+  tertiaryTextColor: '#a6adc8',
+  textColor: '#cdd6f4',
+  nodeTextColor: '#cdd6f4',
+  titleColor: '#cdd6f4',
+  classText: '#cdd6f4',
+  labelTextColor: '#cdd6f4',
+  lineColor: '#a6adc8',
+  defaultLinkColor: '#a6adc8',
+  arrowheadColor: '#a6adc8',
+  actorBkg: '#45475a',
+  actorBorder: '#585b70',
+  actorTextColor: '#cdd6f4',
+  actorLineColor: '#a6adc8',
+  signalColor: '#a6adc8',
+  signalTextColor: '#cdd6f4',
+  loopTextColor: '#cdd6f4',
+  sequenceNumberColor: '#1e1e2e',
+  activationBkgColor: '#585b70',
+  activationBorderColor: '#6c7086',
+  edgeLabelBackground: '#1e1e2e',
+  labelBoxBkgColor: '#1e1e2e',
+  clusterBkg: 'rgba(30, 30, 46, 0.5)',
+  noteBkgColor: 'rgba(249, 226, 175, 0.12)',
+  noteBorderColor: '#f9e2af',
+  noteTextColor: '#cdd6f4',
+  fontFamily:
+    "-apple-system, BlinkMacSystemFont, 'Segoe UI', 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif",
+  fontSize: '16px',
+} as const;
+
+/** 按主题返回对应 Catppuccin themeVariables。 */
+function themeVarsFor(theme: ThemeName): Record<string, unknown> {
+  return theme === 'dark' ? { ...MOCHA_VARS } : { ...LATTE_VARS };
+}
+
 declare global {
   interface Window {
     MermaidRenderer?: MermaidApi;
@@ -102,8 +223,18 @@ async function renderBlock(pre: HTMLPreElement, source: string, theme: ThemeName
   const mermaid = await loadMermaid();
   mermaid.initialize({
     startOnLoad: false,
-    theme: theme === 'dark' ? 'dark' : 'default',
+    // base 主题不硬编码颜色，让 themeVariables 完全控制 Catppuccin 调色板。
+    theme: 'base',
+    darkMode: theme === 'dark',
     securityLevel: 'strict',
+    // flowchart：平滑曲线 + 边缘留白 + 缩放至容器宽度（配合 CSS 消除横向滚动）。
+    flowchart: {
+      curve: 'basis',
+      diagramPadding: 16,
+      useMaxWidth: true,
+      htmlLabels: true,
+    },
+    themeVariables: themeVarsFor(theme),
   });
   const id = `mermaid-svg-${++renderCounter}`;
   const { svg } = await mermaid.render(id, source);