diff --git a/renderer/index.html b/renderer/index.html
index ceadac6..3724dfa 100644
--- a/renderer/index.html
+++ b/renderer/index.html
@@ -91,21 +91,23 @@
       <button id="btn-dismiss" class="banner-btn">忽略</button>
     </div>
 
-    <!-- Sidebar -->
-    <div id="sidebar">
-      <div id="sidebar-header">
-        <span id="sidebar-title">资源管理器</span>
-        <button id="btn-open-folder" class="sidebar-header-btn" title="打开文件夹">
-          <svg width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
-            <path d="M22 19a2 2 0 0 1-2 2H4a2 2 0 0 1-2-2V5a2 2 0 0 1 2-2h5l2 3h9a2 2 0 0 1 2 2z"></path>
-          </svg>
-        </button>
+    <!-- Workspace: Sidebar + Main Content -->
+    <div id="workspace">
+      <!-- Sidebar -->
+      <div id="sidebar">
+        <div id="sidebar-header">
+          <span id="sidebar-title">资源管理器</span>
+          <button id="btn-open-folder" class="sidebar-header-btn" title="打开文件夹">
+            <svg width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+              <path d="M22 19a2 2 0 0 1-2 2H4a2 2 0 0 1-2-2V5a2 2 0 0 1 2-2h5l2 3h9a2 2 0 0 1 2 2z"></path>
+            </svg>
+          </button>
+        </div>
+        <div id="sidebar-tree"></div>
       </div>
-      <div id="sidebar-tree"></div>
-    </div>
 
-    <!-- Main content area -->
-    <div id="main-content">
+      <!-- Main content area -->
+      <div id="main-content">
       <!-- Editor panel -->
       <div id="editor-panel">
         <!-- Search & Replace Bar -->
@@ -143,6 +145,7 @@
         <div id="preview" class="markdown-body"></div>
       </div>
     </div>
+    </div>
 
     <!-- Status bar -->
     <div id="statusbar">
diff --git a/renderer/style.css b/renderer/style.css
index 0ac9930..8d14ffc 100644
--- a/renderer/style.css
+++ b/renderer/style.css
@@ -66,6 +66,7 @@ html, body {
   display: flex;
   flex-direction: column;
   height: 100vh;
+  position: relative;
 }
 
 /* ===== Toolbar ===== */
@@ -297,6 +298,14 @@ html, body {
 }
 
 /* ===== Main Content ===== */
+#workspace {
+  flex: 1;
+  display: flex;
+  flex-direction: row;
+  overflow: hidden;
+  min-height: 0;
+}
+
 #main-content {
   flex: 1;
   display: flex;