diff --git a/index.html b/index.html
index bcce56d..6cba6e8 100644
--- a/index.html
+++ b/index.html
@@ -1,93 +1,97 @@
 <!DOCTYPE html>
 <html>
-  <head>
-    <meta charset="utf-8" />
-    <meta
-      name="viewport"
-      content="width=device-width, initial-scale=1, shrink-to-fit=no"
-    />
-    <title>Makefile 教程</title>
-    <link rel="stylesheet" href="https://unpkg.com/docute@4/dist/docute.css" />
-    <link rel="stylesheet" href="/assets/styles/docs.css" />
-  </head>
-  <body>
-    <div id="docute"></div>
-    <script src="https://unpkg.com/docute@4/dist/docute.js"></script>
-    <script src="https://unpkg.com/docute-google-analytics@1/dist/index.min.js"></script>
-    <script>
-      new Docute({
-        target: '#docute',
-        plugins: [
-          window.location.hostname !== 'localhost' &&
-            docuteGoogleAnalytics('UA-199192487-1'),
-        ].filter(Boolean),
-        highlight: ['makefile', 'bash'],
-        cssVariables: {
-          sidebarWidth: '220px',
+
+<head>
+  <meta charset="utf-8" />
+  <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no" />
+  <title>Makefile 教程</title>
+  <link rel="stylesheet" href="https://unpkg.com/docute@4/dist/docute.css" />
+  <link rel="stylesheet" href="/assets/styles/docs.css" />
+</head>
+
+<body>
+  <div id="docute"></div>
+  <script src="https://unpkg.com/docute@4/dist/docute.js"></script>
+  <!-- Google tag (gtag.js) -->
+  <script async src="https://www.googletagmanager.com/gtag/js?id=G-W55D0DZH3L"></script>
+  <script>
+    window.dataLayer = window.dataLayer || [];
+    function gtag() { dataLayer.push(arguments); }
+    gtag('js', new Date());
+
+    gtag('config', 'G-W55D0DZH3L');
+  </script>
+  <script>
+    new Docute({
+      target: '#docute',
+      highlight: ['makefile', 'bash'],
+      cssVariables: {
+        sidebarWidth: '220px',
+      },
+      nav: [
+        {
+          title: '原作仓库',
+          link: 'https://github.com/theicfire/makefiletutorial',
         },
-        nav: [
-          {
-            title: '原作仓库',
-            link: 'https://github.com/theicfire/makefiletutorial',
-          },
-          {
-            title: '作者推特',
-            link: 'https://twitter.com/chaselambda',
-          },
-          {
-            title: '译作仓库',
-            link: 'https://github.com/gavinliu6/Makefile-Tutorial-zh-CN',
-          },
-        ],
-        sidebar: [
-          {
-            title: '起步',
-            link: '/docs/getting-started',
-          },
-          {
-            title: '目标',
-            link: '/docs/targets',
-          },
-          {
-            title: '自动变量和通配符',
-            link: '/docs/automatic-variables-and-wildcards',
-          },
-          {
-            title: '各种规则',
-            link: '/docs/fancy-rules',
-          },
-          {
-            title: '命令和执行',
-            link: '/docs/commands-and-execution',
-          },
-          {
-            title: '变量（第 2 部分）',
-            link: '/docs/variables-pt-2',
-          },
-          {
-            title: 'Makefiles 的条件判断',
-            link: '/docs/conditional-part-of-makefiles',
-          },
-          {
-            title: '函数',
-            link: '/docs/functions',
-          },
-          {
-            title: '其他特性',
-            link: '/docs/other-features',
-          },
-          {
-            title: 'Makefile Cookbook',
-            link: '/docs/makefile-cookbook',
-          },
-        ],
-        footer: `
+        {
+          title: '作者推特',
+          link: 'https://twitter.com/chaselambda',
+        },
+        {
+          title: '译作仓库',
+          link: 'https://github.com/gavinliu6/Makefile-Tutorial-zh-CN',
+        },
+      ],
+      sidebar: [
+        {
+          title: '起步',
+          link: '/docs/getting-started',
+        },
+        {
+          title: '目标',
+          link: '/docs/targets',
+        },
+        {
+          title: '自动变量和通配符',
+          link: '/docs/automatic-variables-and-wildcards',
+        },
+        {
+          title: '各种规则',
+          link: '/docs/fancy-rules',
+        },
+        {
+          title: '命令和执行',
+          link: '/docs/commands-and-execution',
+        },
+        {
+          title: '变量（第 2 部分）',
+          link: '/docs/variables-pt-2',
+        },
+        {
+          title: 'Makefiles 的条件判断',
+          link: '/docs/conditional-part-of-makefiles',
+        },
+        {
+          title: '函数',
+          link: '/docs/functions',
+        },
+        {
+          title: '其他特性',
+          link: '/docs/other-features',
+        },
+        {
+          title: 'Makefile Cookbook',
+          link: '/docs/makefile-cookbook',
+        },
+      ],
+      footer: `
   <div style="border-top:1px solid var(--border-color);padding-top:30px;margin: 40px 0;color:#999999;font-size: .9rem;">
   &copy; ${new Date().getFullYear()} Translated by <a href="https://gavinliu.me" target="_blank">Gavin Liu</a>.
   💕 The site is built by <a href="https://docute.org/" target="_blank">Docute</a>.
   </div>
   `,
-      })
-    </script>
-  </body>
+    })
+  </script>
+</body>
+
 </html>
