fix: 調整關閉按鈕位置到內容區塊內並使用 sticky 定位

- 使用 position: sticky 讓按鈕在內容區塊內但滾動時固定
- 使用 float: right 讓按鈕靠右對齊
- 更新版本號至 v20250603002

Author: yulin0629

index.html

@@ -8,7 +8,7 @@
     <meta http-equiv="Expires" content="0">
     <meta name="theme-color" content="#000000">
     <title>GitHub Copilot 教學專案</title>
-    <link rel="stylesheet" href="style.css?v=20250603001">
+    <link rel="stylesheet" href="style.css?v=20250603002">
     <script src="https://cdn.jsdelivr.net/npm/marked/marked.min.js"></script>
     <script src="https://cdn.jsdelivr.net/npm/qrcodejs@1.0.0/qrcode.min.js"></script>
 </head>
@@ -344,14 +344,14 @@ <h3 style="font-size: 1.25rem; font-weight: 600; color: #1d1d1f; margin-bottom:
 
     <!-- Markdown Modal -->
     <div id="markdownModal" class="markdown-modal">
-        <button class="markdown-close" onclick="closeMarkdown()" aria-label="關閉"></button>
         <div class="markdown-content">
+            <button class="markdown-close" onclick="closeMarkdown()" aria-label="關閉"></button>
             <div id="markdownBody">
                 <div class="markdown-loading">載入中...</div>
             </div>
         </div>
     </div>
 
-    <script src="script.js?v=20250603001"></script>
+    <script src="script.js?v=20250603002"></script>
 </body>
 </html>

style.css

@@ -660,9 +660,11 @@ body {
 }
 
 .markdown-close {
-    position: fixed;
-    top: 70px;
-    right: calc(5% + 20px);
+    position: sticky;
+    top: 20px;
+    float: right;
+    margin-left: 20px;
+    margin-bottom: 20px;
     width: 36px;
     height: 36px;
     cursor: pointer;