style:修复侧边栏高度溢出问题；修复课件导航条层级过高，浮动在nav上部错误样式

src/views/teacher/AdminDashboard.vue

@@ -191,6 +191,11 @@ const setActiveNavItem = (index: number) => {
 
 // 考试管理菜单切换
 const toggleExamMenu = () => {
+  // 如果当前菜单要展开，先关闭其他菜单
+  if (!examMenuExpanded.value) {
+    studentMenuExpanded.value = false;
+  }
+  
   examMenuExpanded.value = !examMenuExpanded.value;
   activeNavItem.value = 4;
 
@@ -202,6 +207,11 @@ const toggleExamMenu = () => {
 
 // 学员中心菜单切换
 const toggleStudentMenu = (path: string) => {
+  // 如果当前菜单要展开，先关闭其他菜单
+  if (!studentMenuExpanded.value) {
+    examMenuExpanded.value = false;
+  }
+  
   studentMenuExpanded.value = !studentMenuExpanded.value;
   activeNavItem.value = 1;
 
@@ -727,6 +737,10 @@ const updateActiveNavItem = () => {
 </script>
 
 <style scoped>
+.admin-dashboard {
+  position: relative;
+}
+
 .top-image-container {
   position: relative;
   width: 100%;
@@ -855,6 +869,7 @@ const updateActiveNavItem = () => {
   width: 240px;
   height: calc(100vh - var(--top-height, 130px));
   background: #FFFFFF;
+  overflow: auto;
 }
 
 @media screen and (max-width: 768px) {
@@ -871,8 +886,12 @@ const updateActiveNavItem = () => {
 }
 
 .avatar-container {
-  height: 230px;
   position: relative;
+  padding: 20px;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  flex-direction: column;
   /* 移除原来的边框 */
 }
 
@@ -892,13 +911,10 @@ const updateActiveNavItem = () => {
   height: 80px;
   /* 圆角 */
   border-radius: 50%;
-  margin-top: 55px;
-  margin-left: 80px;
-  margin-right: 80px;
+  margin-top: 30px;
 }
 
 .avatar-text {
-  margin-left: 80px;
   height: 31px;
   font-family: AppleSystemUIFont;
   font-size: 20px;

src/views/teacher/course/CourseEditor.vue

@@ -124,6 +124,10 @@ const homeworkExpanded = ref(false)
 
 // 切换作业菜单展开/收起
 const toggleHomework = () => {
+  // 如果要展开作业菜单，先关闭考试菜单
+  if (!homeworkExpanded.value) {
+    practiceExpanded.value = false
+  }
   homeworkExpanded.value = !homeworkExpanded.value
 }
 
@@ -132,6 +136,10 @@ const practiceExpanded = ref(false)
 
 // 切换练考通菜单展开/收起
 const togglePractice = () => {
+  // 如果要展开考试菜单，先关闭作业菜单
+  if (!practiceExpanded.value) {
+    homeworkExpanded.value = false
+  }
   practiceExpanded.value = !practiceExpanded.value
 }
 

src/views/teacher/course/FileViewer.vue

@@ -1,7 +1,7 @@
 <template>
   <div class="file-viewer">
     <!-- 顶部导航栏 -->
-    <div class="header">
+    <div class="header-top">
       <div class="nav-left">
        <n-button quaternary circle size="large" @click="goBack" class="back-button">
             <template #icon>
@@ -630,14 +630,13 @@ onUnmounted(() => {
 }
 
 /* 顶部导航栏 */
-.header {
+.header-top {
   display: flex;
   justify-content: space-between;
   align-items: center;
   padding: 16px 24px;
   border-bottom: 1px solid #e8e8e8;
   background: #fff;
-  z-index: 10;
 }
 
 .nav-left {

src/views/teacher/course/FolderBrowser.vue

@@ -1,7 +1,7 @@
 <template>
   <div class="folder-browser">
     <!-- 顶部导航栏 -->
-    <div class="header">
+    <div class="header-top">
       <div class="nav-left">
         <n-button quaternary circle size="large" @click="goBack" class="back-button">
             <template #icon>
@@ -426,11 +426,6 @@ const findFileById = (files: FileItem[], id: number): FileItem | null => {
 // 加载文件夹数据
 const loadFolder = async (folderId: number) => {
   // 防止重复加载同一个文件夹
-  if (loading.value || (currentFolder.value && currentFolder.value.id === folderId)) {
-    console.log('🔄 跳过重复加载，folderId:', folderId)
-    return
-  }
-  
   console.log('📂 开始加载文件夹，folderId:', folderId)
   loading.value = true
   
@@ -814,9 +809,7 @@ const startUpload = async () => {
     showUploadModal.value = false
     
     // 刷新当前文件夹内容
-    if (currentFolder.value) {
-      loadFolder(currentFolder.value.id)
-    }
+    loadFolder(currentFolder.value.id)
     
   } catch (error) {
     console.error('文件上传失败:', error)
@@ -874,14 +867,13 @@ watch(
 }
 
 /* 顶部导航栏 */
-.header {
+.header-top {
   display: flex;
   justify-content: space-between;
   align-items: center;
   padding: 16px 24px;
   border-bottom: 1px solid #e8e8e8;
   background: #fff;
-  z-index: 10;
 }
 
 .nav-left {