feat: UI调整

src/layouts/MainLayout.js

@@ -30,12 +30,12 @@ const MemoizedAppFooter = memo(AppFooter);
  */
 export default function MainLayout() {
     return (
-        <Box minH="100vh" display="flex" flexDirection="column">
+        <Box flex="1" h="100vh" w="100%" position="relative" display="flex" flexDirection="column">
             {/* 导航栏 - 在所有页面间共享，memo 后不会在路由切换时重新渲染 */}
             <MemoizedHomeNavbar />
 
             {/* 页面内容区域 - flex: 1 占据剩余空间，包含错误边界、懒加载 */}
-            <Box flex="1" w="100%" position="relative" overflow="hidden" pt="72px">
+            <Box flex="1" pt="72px">
                 <ErrorBoundary>
                     <Suspense fallback={<PageLoader message="页面加载中..." />}>
                         <Outlet />
@@ -47,11 +47,11 @@ export default function MainLayout() {
             <MemoizedAppFooter />
 
             {/* 返回顶部按钮 - 滚动超过阈值时显示 */}
-            <BackToTopButton
+            {/* <BackToTopButton
                 scrollThreshold={BACK_TO_TOP_CONFIG.scrollThreshold}
                 position={BACK_TO_TOP_CONFIG.position}
                 zIndex={BACK_TO_TOP_CONFIG.zIndex}
-            />
+            /> */}
         </Box>
     );
 }