write(ui): 全套 dark 主题，配色对齐 notes / cube portal

- 引入 :root --bg/--bg-elev/--bg-card/--border/--text/--accent 等 vars（跟 notes 一致）
- 主要 surface：body / sidebar / editor / preview / input-bar / modal / mobile-bar
- accent 紫 (#c084fc + #7c5cbf) 替代 #5566ee 蓝
- preview markdown：h2-h4 紫，inline code amber，pre block 加 border
- splitter hover 用 accent-strong 紫
- 滚动条暗化

apps/write/frontend/src/styles.css

@@ -1,17 +1,42 @@
+:root {
+  --bg: #0f0f0f;
+  --bg-elev: #161616;
+  --bg-card: #1a1a2e;
+  --bg-hover: #232342;
+  --bg-active: #2a1a3e;
+  --border: #2a2a3a;
+  --border-soft: #1f1f2a;
+  --text: #e0e0e0;
+  --text-dim: #a0a0a0;
+  --text-mute: #666;
+  --accent: #c084fc;
+  --accent-strong: #7c5cbf;
+  --accent-cyan: #06b6d4;
+  --accent-green: #4ade80;
+  --accent-amber: #f59e0b;
+  --accent-red: #ef4444;
+}
+
 * { box-sizing: border-box; }
 html, body, #app { height: 100%; margin: 0; width: 100%; overflow-x: hidden; }
 body {
-  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC',
+  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC',
     'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
-  background: #fafafa;
+  background: var(--bg);
-  color: #222;
+  color: var(--text);
   font-size: 14px;
+  -webkit-font-smoothing: antialiased;
 }
 .app { max-width: 100vw; overflow-x: hidden; }
 
 button { font: inherit; cursor: pointer; }
 textarea, input { font: inherit; }
 
+::-webkit-scrollbar { width: 8px; height: 8px; }
+::-webkit-scrollbar-track { background: transparent; }
+::-webkit-scrollbar-thumb { background: var(--border); border-radius: 4px; }
+::-webkit-scrollbar-thumb:hover { background: var(--text-mute); }
+
 /* ====== layout ====== */
 
 .app {
@@ -21,8 +46,8 @@ textarea, input { font: inherit; }
 }
 
 .sidebar {
-  border-right: 1px solid #e5e5e5;
+  border-right: 1px solid var(--border-soft);
-  background: #fff;
+  background: var(--bg-elev);
   display: flex;
   flex-direction: column;
   min-width: 0;
@@ -30,7 +55,7 @@ textarea, input { font: inherit; }
 
 .sidebar-header {
   padding: 14px 16px;
-  border-bottom: 1px solid #eee;
+  border-bottom: 1px solid var(--border-soft);
   display: flex;
   align-items: center;
   gap: 8px;
@@ -38,13 +63,14 @@ textarea, input { font: inherit; }
 .sidebar-header h1 { margin: 0; font-size: 16px; font-weight: 600; }
 .sidebar-header .new-btn {
   margin-left: auto;
-  border: 1px solid #ddd;
+  border: 1px solid var(--border);
-  background: #fff;
+  background: var(--bg-elev);
+  color: var(--text-dim);
   padding: 4px 10px;
   border-radius: 6px;
   font-size: 13px;
 }
-.sidebar-header .new-btn:hover { background: #f5f5f5; }
+.sidebar-header .new-btn:hover { background: var(--bg-hover); color: var(--text); }
 
 .doc-list { flex: 1; overflow-y: auto; padding: 6px; }
 .doc-item {
@@ -56,20 +82,21 @@ textarea, input { font: inherit; }
   display: flex;
   align-items: center;
   gap: 8px;
+  color: var(--text-dim);
 }
-.doc-item:hover { background: #f3f3f3; }
+.doc-item:hover { background: var(--bg-card); color: var(--text); }
-.doc-item.active { background: #e8efff; }
+.doc-item.active { background: var(--bg-active); color: var(--accent); }
 .doc-item .title {
   flex: 1;
   white-space: nowrap;
   overflow: hidden;
   text-overflow: ellipsis;
 }
-.doc-item .meta { font-size: 11px; color: #888; }
+.doc-item .meta { font-size: 11px; color: var(--text-mute); }
 .doc-item .del {
   border: none;
   background: transparent;
-  color: #c44;
+  color: var(--accent-red);
   font-size: 12px;
   visibility: hidden;
 }
@@ -82,7 +109,7 @@ textarea, input { font: inherit; }
   grid-template-rows: 1fr 6px var(--input-h, 140px);
   min-width: 0;
   min-height: 0;
-  background: #fafafa;
+  background: var(--bg);
   overflow: hidden;
 }
 
@@ -95,22 +122,18 @@ textarea, input { font: inherit; }
   grid-template-columns: var(--editor-fr, 1fr) 6px var(--preview-fr, 1fr);
   grid-template-rows: auto 1fr;
   min-height: 0;
-  border-bottom: 1px solid #e5e5e5;
+  border-bottom: 1px solid var(--border-soft);
 }
 
 /* 拖拽分隔条 */
 .splitter {
-  background: #e5e5e5;
+  background: var(--border-soft);
   cursor: col-resize;
   transition: background 0.12s;
   user-select: none;
 }
-.splitter:hover { background: #b0c5ff; }
+.splitter:hover { background: var(--accent-strong); }
-.splitter-main { /* sidebar | workspace */ }
+.splitter-input { cursor: row-resize; }
-.splitter-editor { /* editor | preview */ }
-.splitter-input { /* editor-pane | input-bar 横向分隔 */
-  cursor: row-resize;
-}
 @media (max-width: 768px) {
   .splitter { display: none; }
 }
@@ -118,8 +141,8 @@ textarea, input { font: inherit; }
 .title-row {
   grid-column: 1 / -1;
   padding: 10px 16px;
-  border-bottom: 1px solid #eee;
+  border-bottom: 1px solid var(--border-soft);
-  background: #fff;
+  background: var(--bg-elev);
 }
 .title-row input {
   width: 100%;
@@ -128,7 +151,9 @@ textarea, input { font: inherit; }
   font-size: 16px;
   font-weight: 600;
   background: transparent;
+  color: var(--text);
 }
+.title-row input::placeholder { color: var(--text-mute); }
 
 .editor, .preview {
   min-height: 0;
@@ -136,10 +161,9 @@ textarea, input { font: inherit; }
   padding: 16px;
 }
 .editor {
-  border-right: 1px solid #e5e5e5;
+  background: var(--bg-elev);
-  background: #fff;
+  overflow-x: hidden;
 }
-.editor { overflow-x: hidden; }
 .editor textarea {
   width: 100%;
   max-width: 100%;
@@ -151,33 +175,40 @@ textarea, input { font: inherit; }
   font-size: 13px;
   line-height: 1.6;
   background: transparent;
+  color: var(--text);
   word-break: break-all;
 }
+.editor textarea::placeholder { color: var(--text-mute); }
 .preview {
-  background: #fff;
+  background: var(--bg);
+  color: var(--text);
   line-height: 1.6;
   overflow-x: hidden;
   word-wrap: break-word;
   overflow-wrap: anywhere;
 }
-.preview h1, .preview h2, .preview h3 { margin: 18px 0 8px; }
+.preview h1, .preview h2, .preview h3 { margin: 18px 0 8px; color: var(--accent); }
 .preview p { margin: 8px 0; }
+.preview a { color: var(--accent-cyan); }
+.preview strong { color: var(--accent); }
 .preview pre {
-  background: #f5f5f5; padding: 10px; border-radius: 6px;
+  background: var(--bg-elev); padding: 10px; border-radius: 6px;
   font-size: 12px; overflow-x: auto;
   max-width: 100%;
+  border: 1px solid var(--border-soft);
 }
-.preview code { background: #f5f5f5; padding: 1px 4px; border-radius: 3px; font-size: 12px; }
+.preview code { background: var(--bg-elev); padding: 1px 4px; border-radius: 3px; font-size: 12px; color: var(--accent-amber); }
-.preview pre code { background: transparent; padding: 0; word-wrap: normal; overflow-wrap: normal; }
+.preview pre code { background: transparent; padding: 0; word-wrap: normal; overflow-wrap: normal; color: var(--text); }
-.preview blockquote { border-left: 3px solid #ddd; margin: 8px 0; padding: 4px 12px; color: #555; }
+.preview blockquote { border-left: 3px solid var(--accent-strong); margin: 8px 0; padding: 4px 12px; color: var(--text-dim); }
 .preview img { max-width: 100%; height: auto; }
 .preview table { display: block; max-width: 100%; overflow-x: auto; }
+.preview hr { border: none; border-top: 1px solid var(--border); margin: 16px 0; }
 
 /* ====== input bar ====== */
 
 .input-bar {
-  background: #fff;
+  background: var(--bg-elev);
-  border-top: 1px solid #e5e5e5;
+  border-top: 1px solid var(--border-soft);
   padding: 10px 12px;
 }
 .input-row { display: flex; gap: 8px; align-items: flex-end; min-width: 0; }
@@ -185,39 +216,43 @@ textarea, input { font: inherit; }
   flex: 1 1 0;
   min-width: 0;
   min-height: 40px;
-  max-height: 160px;
+  max-height: 100%;
   resize: none;
   padding: 9px 12px;
-  border: 1px solid #ddd;
+  border: 1px solid var(--border);
+  background: var(--bg);
+  color: var(--text);
   border-radius: 8px;
   outline: none;
   font-size: 14px;
   line-height: 1.4;
 }
-.input-row textarea:focus { border-color: #6b7cff; }
+.input-row textarea::placeholder { color: var(--text-mute); }
+.input-row textarea:focus { border-color: var(--accent-strong); }
 
 .btn {
   height: 40px;
   padding: 0 14px;
   border-radius: 8px;
-  border: 1px solid #ddd;
+  border: 1px solid var(--border);
-  background: #fff;
+  background: var(--bg-elev);
+  color: var(--text-dim);
   font-size: 14px;
 }
-.btn:hover { background: #f5f5f5; }
+.btn:hover { background: var(--bg-hover); color: var(--text); }
-.btn.primary { background: #5566ee; border-color: #4455dd; color: #fff; }
+.btn.primary { background: var(--accent-strong); border-color: var(--accent-strong); color: #fff; }
-.btn.primary:hover { background: #4455dd; }
+.btn.primary:hover { background: var(--accent); border-color: var(--accent); color: #fff; }
-.btn.primary:disabled { background: #aaa; border-color: #aaa; cursor: not-allowed; }
+.btn.primary:disabled { background: var(--bg-card); border-color: var(--border); color: var(--text-mute); cursor: not-allowed; }
 .btn.mic { width: 44px; padding: 0; }
-.btn.mic.on { background: #ee5566; border-color: #dd4455; color: #fff; }
+.btn.mic.on { background: var(--accent-red); border-color: var(--accent-red); color: #fff; }
 
 .status {
   font-size: 12px;
-  color: #666;
+  color: var(--text-mute);
   padding: 4px 4px 0;
   min-height: 18px;
 }
-.status.err { color: #c44; }
+.status.err { color: var(--accent-red); }
 
 /* ====== mobile-only chrome ====== */
 
@@ -226,14 +261,15 @@ textarea, input { font: inherit; }
   align-items: center;
   gap: 8px;
   padding: 8px 12px;
-  background: #fff;
+  background: var(--bg-elev);
-  border-bottom: 1px solid #e5e5e5;
+  border-bottom: 1px solid var(--border-soft);
   padding-top: max(8px, env(safe-area-inset-top));
 }
 .mobile-bar .hamburger,
 .mobile-bar .pane-tabs button {
-  border: 1px solid #ddd;
+  border: 1px solid var(--border);
-  background: #fff;
+  background: var(--bg-elev);
+  color: var(--text-dim);
   border-radius: 6px;
   font-size: 14px;
   padding: 6px 10px;
@@ -244,9 +280,9 @@ textarea, input { font: inherit; }
   gap: 4px;
 }
 .mobile-bar .pane-tabs button.active {
-  background: #5566ee;
+  background: var(--accent-strong);
   color: #fff;
-  border-color: #4455dd;
+  border-color: var(--accent-strong);
 }
 .mobile-bar .doc-title {
   flex: 1 1 0;
@@ -257,12 +293,12 @@ textarea, input { font: inherit; }
   font-weight: 600;
   font-size: 14px;
 }
-.mobile-bar .doc-title input { min-width: 0; }
+.mobile-bar .doc-title input { min-width: 0; color: var(--text); }
 
 .sidebar-backdrop {
   display: none;
   position: fixed; inset: 0;
-  background: rgba(0,0,0,0.35);
+  background: rgba(0,0,0,0.55);
   z-index: 50;
 }
 
@@ -283,24 +319,22 @@ textarea, input { font: inherit; }
     top: 0; left: 0; bottom: 0;
     width: 78vw;
     max-width: 320px;
-    border-right: 1px solid #e5e5e5;
+    border-right: 1px solid var(--border-soft);
     border-bottom: none;
     transform: translateX(-100%);
     transition: transform 0.2s ease;
     z-index: 60;
-    box-shadow: 2px 0 8px rgba(0,0,0,0.1);
+    box-shadow: 2px 0 8px rgba(0,0,0,0.5);
   }
   .app.drawer-open .sidebar { transform: translateX(0); }
   .app.drawer-open .sidebar-backdrop { display: block; }
 
-  /* workspace fills the screen; editor + preview overlay each other,
-     pane-tabs picks which one shows */
   .editor-pane {
     grid-template-columns: 1fr;
     grid-template-rows: 1fr;
     position: relative;
   }
-  .title-row { display: none; }  /* title shows in the mobile-bar instead */
+  .title-row { display: none; }
 
   .editor, .preview {
     grid-column: 1;
@@ -314,14 +348,13 @@ textarea, input { font: inherit; }
   .app.pane-editor .editor { display: block; }
   .app.pane-preview .preview { display: block; }
 
-  /* input bar honors safe area at bottom */
   .input-bar {
     padding-bottom: max(10px, env(safe-area-inset-bottom));
   }
   .input-row textarea {
-    font-size: 16px;  /* iOS won't zoom in if >= 16px */
+    font-size: 16px;
   }
-  .btn { height: 44px; }  /* easier thumb target */
+  .btn { height: 44px; }
   .btn.mic { width: 48px; }
 }
 
@@ -329,17 +362,27 @@ textarea, input { font: inherit; }
 
 .modal-backdrop {
   position: fixed; inset: 0;
-  background: rgba(0,0,0,0.4);
+  background: rgba(0,0,0,0.7);
   display: flex; align-items: center; justify-content: center;
   z-index: 100;
+  backdrop-filter: blur(2px);
 }
 .modal {
-  background: #fff; padding: 20px; border-radius: 10px;
+  background: var(--bg-card);
+  border: 1px solid var(--border);
+  padding: 24px;
+  border-radius: 12px;
   width: 360px; max-width: 90vw;
+  box-shadow: 0 12px 40px rgba(0,0,0,0.5);
 }
-.modal h2 { margin: 0 0 12px; font-size: 16px; }
+.modal h2 { margin: 0 0 12px; font-size: 16px; color: var(--accent); }
 .modal input {
-  width: 100%; padding: 8px 10px; border: 1px solid #ddd; border-radius: 6px;
+  width: 100%; padding: 9px 12px;
+  border: 1px solid var(--border);
+  background: var(--bg-elev);
+  color: var(--text);
+  border-radius: 6px;
   margin-bottom: 12px; outline: none;
 }
+.modal input:focus { border-color: var(--accent-strong); }
 .modal-actions { display: flex; gap: 8px; justify-content: flex-end; }