docs update

packages/artplayer/src/player/aspectRatioMix.js

@@ -8,7 +8,7 @@ export default function aspectRatioMix(art, player) {
     } = art;
 
     Object.defineProperty(player, 'aspectRatioState', {
-        get: () => $player.dataset.aspectRatio,
+        get: () => $player.dataset.aspectRatio || '',
     });
 
     Object.defineProperty(player, 'aspectRatio', {

packages/artplayer/src/style/pip.scss

@@ -56,6 +56,7 @@
         }
 
         .artplayer-mask {
+            display: flex;
             align-items: center;
             justify-content: center;
             .art-icon-playBig {