refactor: improve hot zone for theme switch

Author: Wxh16144

src/client/theme-default/slots/ColorSwitch/index.less

@@ -50,11 +50,12 @@
 
   select {
     position: absolute;
-    top: 0;
-    left: 0;
+    inset: 0 15%;
     opacity: 0;
-    max-width: 100%;
-    max-height: 16px;
+    width: 100%;
+    min-width: 16px;
+    max-width: 70%;
+    height: 16px;
     cursor: pointer;
   }
 }