修复应用缩放有黑边区域

src/App.vue

@@ -965,7 +965,7 @@ registerTauriListener("menu-event", (event) => {
       />
 
       <!-- Right: Editor area -->
-      <main class="flex-1 flex flex-col overflow-hidden relative">
+      <main class="flex-1 flex flex-col overflow-hidden relative editor-area">
         <!-- ════════════════ Custom title bar / toolbar ════════════════ -->
         <div
             class="editor-titlebar flex w-full items-center h-10 pl-3 pr-0 select-none shrink-0"
@@ -1239,6 +1239,10 @@ registerTauriListener("menu-event", (event) => {
   border-bottom: 1px solid var(--app-border-strong);
 }
 
+.editor-area {
+  background: var(--app-bg);
+}
+
 .app-footer {
   border-top: 1px solid var(--app-border);
   background: color-mix(in srgb, var(--app-sidebar-bg) 72%, transparent);

src/components/MarkdownEditor.vue

@@ -687,7 +687,7 @@ defineExpose({
 <template>
   <div
     ref="scrollRef"
-    class="flex-1 w-full h-full overflow-auto"
+    class="flex-1 w-full h-full overflow-auto markdown-editor-scroll"
     @wheel.passive
     @keydown.capture="onRootKeydown"
   >
@@ -783,6 +783,11 @@ defineExpose({
 </template>
 
 <style>
+/* ── Scroll container ────────────────────────────────────────────── */
+.markdown-editor-scroll {
+  background: var(--app-bg);
+}
+
 /* ── Markdown Preview Styles (warm palette) ─────────────────────── */
 
 .markdown-preview {