update docs

packages/artplayer/src/setting/subtitleOffset.js

@@ -1,3 +1,5 @@
+import { inverseClass, queryAll } from '../utils';
+
 export default function subtitleOffset(art) {
     const { i18n, icons } = art;
 
@@ -7,12 +9,21 @@ export default function subtitleOffset(art) {
         icon: icons.subtitle,
         selector: [-5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5].map((item) => {
             return {
+                value: item,
+                default: item === art.subtitleOffset,
                 html: item === 0 ? i18n.get('Normal') : item,
-                default: item === 0,
-                onSelect() {
-                    art.subtitleOffset = item;
-                },
             };
         }),
+        onSelect(item) {
+            art.subtitleOffset = item.value;
+        },
+        mounted: ($panel) => {
+            art.on('subtitleOffset', (value) => {
+                const $current = queryAll('.art-setting-item', $panel).find((item) => item.dataset.value === value);
+                if ($current) {
+                    inverseClass($current, 'art-current');
+                }
+            });
+        },
     };
 }