style: popover bgColor is too close to common (#5364)

修复Dark主题下，弹出层的背景色与主体背景色太过接近的问题

packages/@core/base/design/src/design-tokens/dark.css

@@ -15,7 +15,11 @@
   --card-foreground: 210 40% 98%;
 
   /* Background color for popovers such as <DropdownMenu />, <HoverCard />, <Popover /> */
-  --popover: 222.82deg 8.43% 12.27%;
+
+  /* --popover: 222.82deg 8.43% 12.27%; */
+
+  /* 弹出层的背景色与主题区域背景色太过接近  */
+  --popover: 0 0 14.2%;
   --popover-foreground: 210 40% 98%;
 
   /* Muted backgrounds such as <TabsList />, <Skeleton /> and <Switch /> */