update danmuku style

packages/artplayer-plugin-danmuku/src/style.less

@@ -1,7 +1,7 @@
 .art-danmuku-emitter {
     position: relative;
     display: flex;
-    height: 30px;
+    height: 34px;
     width: 100%;
     font-size: 12px;
     line-height: 1;
@@ -42,7 +42,7 @@
     .art-danmuku-style {
         position: relative;
         display: flex;
-        width: 30px;
+        width: 34px;
         align-items: center;
         justify-content: center;