feat: 添加置顶置底导航按钮

www/style.css

@@ -585,12 +585,24 @@ body {
 /* 功能开关栏 */
 .feature-bar {
   display: flex;
+  justify-content: space-between;
+  align-items: center;
   gap: 8px;
   padding: 8px 16px;
   background: rgba(255,255,255,0.95);
   border-top: 1px solid var(--border-color);
 }
 
+.feature-left {
+  display: flex;
+  gap: 8px;
+}
+
+.feature-right {
+  display: flex;
+  gap: 4px;
+}
+
 .feature-btn {
   display: flex;
   align-items: center;
@@ -620,6 +632,18 @@ body {
   flex-shrink: 0;
 }
 
+/* 导航按钮样式 */
+.nav-btn {
+  padding: 6px 8px;
+  min-width: 32px;
+}
+
+.nav-btn:hover {
+  background: var(--primary);
+  border-color: var(--primary);
+  color: white;
+}
+
 /* 思考内容块 */
 .thinking-block {
   margin-bottom: 12px;