style(docs): adjust sidebar spacing and fix relative links

Update CSS selectors to be more specific and remove redundant parent selectors
Change absolute links to relative paths in index.md for better portability

docs/index.md

@@ -39,25 +39,25 @@ features:
     <div class="stage-icon">🌱</div>
     <h3>Stage 0: 纯新手</h3>
     <p>适合产品、运营及非技术背景。通过做游戏理解 AI 编程逻辑，建立信心。</p>
-    <a href="/stage-0/0.1-learning-map/">查看详情 →</a>
+    <a href="./stage-0/0.1-learning-map/">查看详情 →</a>
   </div>
   <div class="stage-card">
     <div class="stage-icon">🎨</div>
     <h3>Stage 1: AI 产品经理</h3>
     <p>掌握 Vibe Coding 工作流。学会拆解需求，独立完成高保真 Web 应用原型。</p>
-    <a href="/stage-1/1.1-introduction-to-ai-ide/">查看详情 →</a>
+    <a href="./stage-1/1.1-introduction-to-ai-ide/">查看详情 →</a>
   </div>
   <div class="stage-card">
     <div class="stage-icon">💻</div>
     <h3>Stage 2: 初中级开发</h3>
     <p>深入全栈开发。前端组件化、数据库设计、后端 API 开发与部署上线。</p>
-    <a href="/project/chapter4/chapter4-lets-build-hogwarts-portraits">查看详情 →</a>
+    <a href="./stage-2/frontend/2.0-lovart-assets/">查看详情 →</a>
   </div>
   <div class="stage-card">
     <div class="stage-icon">🚀</div>
     <h3>Stage 3: 高级开发</h3>
     <p>构建复杂跨平台应用。微信小程序实战，挑战更高阶的 AI 原生应用开发。</p>
-    <a href="/stage-3/3.3-how-to-build-a-wechat-miniprogram/example1/index">查看详情 →</a>
+    <a href="./stage-3/core-skills/3.1-mcp-claudecode-skills/">查看详情 →</a>
   </div>
 </div>