fix: 鸿蒙设备视频沉浸式视频色值与按钮接近的时候，整个顶部图标及tab按钮完全看不见

@@ -232,15 +232,15 @@ export struct VideoChannelPage {
       .backgroundColor(Color.Transparent)
       .backgroundColor(Color.Transparent)
 
 
     }
     }
-    //顶部渐变遮罩
-    // .linearGradient({
-    //   colors: [
-    //     ['rgba(0, 0, 0, 0.0)', 0.0], ['rgba(0, 0, 0, 0.3)', 1.0]
-    //   ]
-    // })
     .zIndex(20)
     .zIndex(20)
-    .height($r('app.float.top_tab_bar_height_common'))
-    .margin({
+    .height(44 + px2vp(this.topSafeHeight))
+    //顶部渐变遮罩
+    .linearGradient({
+      direction: GradientDirection.Top, // 渐变方向
+      colors: this.currentTopNavSelectedIndex === 0 ? [['rgba(18, 18, 18, 0)', 0],
+        ['rgba(18, 18, 18, 0.5)', 1.0]] : []// 数组末尾元素占比小于1时满足重复着色效果
+    })
+    .padding({
       top: px2vp(this.topSafeHeight)
       top: px2vp(this.topSafeHeight)
     })
     })
     .visibility(this.displayDirection === DisplayDirection.VERTICAL ? Visibility.Visible : Visibility.None)
     .visibility(this.displayDirection === DisplayDirection.VERTICAL ? Visibility.Visible : Visibility.None)