diff --git a/DEV_FAQ.md b/DEV_FAQ.md
index 52f6ac0797..05fbbbd811 100644
--- a/DEV_FAQ.md
+++ b/DEV_FAQ.md
@@ -25,3 +25,11 @@ pnpm link --global element-plus
 ```
 
 > More info see [pnpm link](https://pnpm.io/cli/link).
+
+## Theme
+
+We should not write Chinese comments in scss files.
+
+It will generate warning `@charset "UTF-8";` in the header of css file when built with vite.
+
+> More info see [#3219](https://github.com/element-plus/element-plus/issues/3219).
diff --git a/packages/theme-chalk/src/checkbox.scss b/packages/theme-chalk/src/checkbox.scss
index 7af0c8cb39..58d73239d7 100644
--- a/packages/theme-chalk/src/checkbox.scss
+++ b/packages/theme-chalk/src/checkbox.scss
@@ -180,7 +180,7 @@ $checkbox-bordered-input-width: map.merge(
       }
     }
     @include when(focus) {
-      /*focus时 视觉上区分*/
+      // Visually distinguish when focus
       .#{$namespace}-checkbox__inner {
         border-color: var(--el-checkbox-input-border-color-hover);
       }