feat: adjust mobile layout

src/components/MobileHeader.tsx

@@ -14,10 +14,29 @@ interface MobileHeaderProps {
 const MobileHeader = ({ showBackButton = false }: MobileHeaderProps) => {
   const { siteName } = useSite();
   return (
-    <header className='md:hidden relative w-full bg-white/70 backdrop-blur-xl border-b border-gray-200/50 shadow-sm dark:bg-gray-900/70 dark:border-gray-700/50'>
+    <header className='md:hidden fixed top-0 left-0 right-0 z-[999] w-full bg-white/70 backdrop-blur-xl border-b border-gray-200/50 shadow-sm dark:bg-gray-900/70 dark:border-gray-700/50'>
       <div className='h-12 flex items-center justify-between px-4'>
-        {/* 左侧：返回按钮和设置按钮 */}
+        {/* 左侧：搜索按钮、返回按钮和设置按钮 */}
         <div className='flex items-center gap-2'>
+          <Link
+            href='/search'
+            className='w-10 h-10 p-2 rounded-full flex items-center justify-center text-gray-600 hover:bg-gray-200/50 dark:text-gray-300 dark:hover:bg-gray-700/50 transition-colors'
+          >
+            <svg
+              className='w-full h-full'
+              fill='none'
+              stroke='currentColor'
+              viewBox='0 0 24 24'
+              xmlns='http://www.w3.org/2000/svg'
+            >
+              <path
+                strokeLinecap='round'
+                strokeLinejoin='round'
+                strokeWidth={2}
+                d='M21 21l-6-6m2-5a7 7 0 11-14 0 7 7 0 0114 0z'
+              />
+            </svg>
+          </Link>
           {showBackButton && <BackButton />}
         </div>