move the remaining light panels onto the dark tokens

The scroll-to-bottom control, the approval and queue float panels, and
the inline code chips still carried the light-theme fills (#ffffff,
rgba(255,255,255,.94/.68)) with .dark overrides pinned to old greys.
Point all of them at --bg-card and its rgb triple so the alpha layers
keep working, then drop the overrides that became identical to the base
rule.

Low-alpha white overlays are left alone — on a dark surface they read as
a lift, which is the intent.

packages/client/src/components/hermes/chat/HistoryMessageList.vue

@@ -301,15 +301,11 @@ defineExpose({
   justify-content: center;
   border-radius: 999px;
   border: 1px solid rgba(var(--accent-primary-rgb), 0.24);
-  background: rgba(255, 255, 255, 0.94);
+  background: rgba(var(--bg-card-rgb), 0.94);
   color: var(--accent-primary);
   box-shadow: 0 10px 28px rgba(0, 0, 0, 0.16);
   padding: 0;
   cursor: pointer;
-
-  .dark & {
-    background: rgba(38, 38, 38, 0.94);
-  }
 }
 
 .scroll-bottom-button:hover {

packages/client/src/components/hermes/chat/MessageList.vue

@@ -893,15 +893,11 @@ defineExpose({
   justify-content: center;
   border-radius: 999px;
   border: 1px solid rgba(var(--accent-primary-rgb), 0.24);
-  background: rgba(255, 255, 255, 0.94);
+  background: rgba(var(--bg-card-rgb), 0.94);
   color: var(--accent-primary);
   box-shadow: 0 10px 28px rgba(0, 0, 0, 0.16);
   padding: 0;
   cursor: pointer;
-
-  .dark & {
-    background: rgba(38, 38, 38, 0.94);
-  }
 }
 
 .scroll-bottom-button:hover {
@@ -920,13 +916,9 @@ defineExpose({
   padding: 10px;
   border: 1px solid rgba(var(--accent-info-rgb), 0.22);
   border-radius: 16px;
-  background: #ffffff;
+  background: var(--bg-card);
   box-shadow: 0 14px 40px rgba(0, 0, 0, 0.14);
   backdrop-filter: blur(14px);
-
-  .dark & {
-    background: #262626;
-  }
 }
 
 .approval-float-panel {
@@ -990,7 +982,7 @@ defineExpose({
   font-size: 11px;
   line-height: 1.45;
   color: $text-primary;
-  background: rgba(255, 255, 255, 0.68);
+  background: rgba(var(--bg-card-rgb), 0.68);
   border: 1px solid $border-color;
   border-radius: 11px;
   padding: 8px 10px;
@@ -1084,7 +1076,7 @@ defineExpose({
   min-height: 34px;
   padding: 7px 8px;
   border-radius: 11px;
-  background: rgba(255, 255, 255, 0.68);
+  background: rgba(var(--bg-card-rgb), 0.68);
   color: $text-primary;
 
   .dark & {

packages/client/src/components/hermes/chat/SessionListItem.vue

@@ -403,7 +403,7 @@ onUnmounted(() => {
   padding: 2px;
   border-radius: inherit;
   object-fit: contain;
-  background: #fff;
+  background: var(--bg-card);
 }
 
 @keyframes rainbow-glow {

packages/client/src/components/hermes/group-chat/GroupChatPanel.vue

@@ -932,10 +932,6 @@ export default defineComponent({ components: { CreateRoomForm } })
     color: $text-secondary;
     background-color: $bg-card-hover;
     border-radius: $radius-sm;
-
-    .dark & {
-        background-color: rgba(255, 255, 255, 0.06);
-    }
 }
 
 .context-stop-btn {
@@ -968,13 +964,9 @@ export default defineComponent({ components: { CreateRoomForm } })
     padding: 10px;
     border: 1px solid rgba(var(--accent-primary-rgb), 0.24);
     border-radius: 16px;
-    background: #ffffff;
+    background: var(--bg-card);
     box-shadow: 0 14px 40px rgba(0, 0, 0, 0.14);
     backdrop-filter: blur(14px);
-
-    .dark & {
-        background: #262626;
-    }
 }
 
 .approval-float-header {
@@ -1029,14 +1021,10 @@ export default defineComponent({ components: { CreateRoomForm } })
     font-size: 11px;
     line-height: 1.45;
     color: $text-primary;
-    background: rgba(255, 255, 255, 0.68);
+    background: rgba(var(--bg-card-rgb), 0.68);
     border: 1px solid $border-color;
     border-radius: 11px;
     padding: 8px 10px;
-
-    .dark & {
-        background: rgba(255, 255, 255, 0.08);
-    }
 }
 
 .approval-float-actions {

packages/client/src/components/hermes/group-chat/GroupMessageList.vue

@@ -185,15 +185,11 @@ defineExpose({ scrollToBottom })
     justify-content: center;
     border-radius: 999px;
     border: 1px solid rgba(var(--accent-primary-rgb), 0.24);
-    background: rgba(255, 255, 255, 0.94);
+    background: rgba(var(--bg-card-rgb), 0.94);
     color: var(--accent-primary);
     box-shadow: 0 10px 28px rgba(0, 0, 0, 0.16);
     padding: 0;
     cursor: pointer;
-
-    .dark & {
-        background: rgba(38, 38, 38, 0.94);
-    }
 }
 
 .scroll-bottom-button:hover {

packages/client/src/styles/variables.scss

@@ -13,6 +13,8 @@
   --bg-card: oklch(0.185 0.014 248);     // 容器 / 输入区（比页面更亮，向上浮）
   --bg-card-hover: oklch(0.225 0.016 246);
   --bg-input: oklch(0.105 0.012 252);    // 输入框，比卡片更沉，形成凹陷感
+  // 半透明浮层需要 rgb 三元组才能拼 alpha，OKLCH 无法直接拆。
+  --bg-card-rgb: 40, 44, 56;
 
   // Borders — 发丝线分两档
   --border-color: oklch(0.305 0.018 242);