feat(toc): add sticky positioning and entry animation for improved UX

templates/post.html

@@ -4,8 +4,8 @@
   th:replace="~{modules/layout :: html(title = |${post.spec.title} - ${site.title}|, header = null, content = ~{::content}, footer = null)}"
 >
   <th:block th:fragment="content">
-    <div class="post" x-data="postLineNum" x-init="init()">
-      <!-- 目录组件 -->
+    <!-- 目录组件 -->
+    <div class="post-toc-sticky">
       <div class="post-toc" x-data="postToc" x-init="init()">
         <div class="toc-header">
           <span class="toc-header__icon">&lt;&gt;</span>
@@ -25,6 +25,8 @@
           </template>
         </ul>
       </div>
+    </div>
+    <div class="post" x-data="postLineNum" x-init="init()">
       <h1 class="post-title" th:text="'< ' + ${post.spec.title} + ' >'">Post Title</h1>
       <div class="post-meta">
         <span class="post-date" th:text="${#dates.format(post.spec.publishTime,'yyyy-MM-dd')}"> publishTime </span>