style: keep tab label highlighted after losing focus

This commit closes #108

src/app/player/components/channel-list-container/channel-list-container.component.html

@@ -1,4 +1,4 @@
-<mat-tab-group>
+<mat-tab-group color="primary" backgroundColor="primary">
     <mat-tab [label]="'CHANNELS.ALL_CHANNELS' | translate">
         <mat-list>
             <mat-list-item>

src/styles.scss

@@ -32,6 +32,12 @@ html {
     height: 54px;
 }
 
+::ng-deep {
+    .mat-tab-label-active {
+        opacity: 1 !important;
+    }
+}
+
 input,
 button,
 textarea,