Move and restyle 'URL 转换器' link in header

The 'URL 转换器' link was moved from the bottom of the popup to the header section and given new styles for improved visibility and consistency with other header elements.

popup.html

@@ -55,6 +55,38 @@
         background: rgba(255, 255, 255, 0.05);
       }
 
+      .header .link-item {
+        display: inline-flex;
+        align-items: center;
+        justify-content: center;
+        margin-bottom: 10px;
+        padding: 6px 12px;
+        font-size: 12px;
+        opacity: 0.8;
+        transition: opacity 0.2s ease;
+        border-radius: 6px;
+        background: var(--container-bg);
+        border: 1px solid var(--container-border);
+        text-decoration: none;
+        color: var(--text-color);
+      }
+
+      .header .link-item:hover {
+        opacity: 1;
+        background: var(--hover-bg);
+        border-color: rgba(255, 255, 255, 0.3);
+        transform: translateY(-1px);
+      }
+
+      .header .link-item .link-icon {
+        margin-right: 6px;
+        font-size: 14px;
+      }
+
+      .header .link-item .link-text {
+        font-size: 12px;
+      }
+
       .header h1 {
         margin: 0;
         font-size: 20px;
@@ -371,6 +403,15 @@
   </head>
   <body>
     <div class="header">
+      <a
+        href="https://xuc.xi-xu.me/"
+        target="_blank"
+        class="link-item"
+        style="margin-bottom: 10px; display: inline-block"
+      >
+        <span class="link-icon">🔗</span>
+        <span class="link-text">URL 转换器</span>
+      </a>
       <h1>Xget Now</h1>
     </div>
 
@@ -570,10 +611,6 @@
             <span class="link-icon">📖</span>
             <span class="link-text">扩展存储库</span>
           </a>
-          <a href="https://xuc.xi-xu.me/" target="_blank" class="link-item">
-            <span class="link-icon">🔗</span>
-            <span class="link-text">URL 转换器</span>
-          </a>
         </div>
       </div>