Lot of visual improvements.

src/app/app.module.ts

@@ -23,6 +23,7 @@ import {MatCheckboxModule} from '@angular/material/checkbox';
 import { TaskListService } from './core/service/task-list.service';
 import { StorePersistenceService } from './core/service/store-persistence.service';
 import {MatTooltipModule} from '@angular/material/tooltip'; 
+import {MatRippleModule} from '@angular/material/core'; 
 
 @NgModule({
   declarations: [
@@ -47,7 +48,8 @@ import {MatTooltipModule} from '@angular/material/tooltip';
     ReactiveFormsModule,
     MatSnackBarModule,
     MatCheckboxModule,
-    MatTooltipModule
+    MatTooltipModule,
+    MatRippleModule
   ],
   providers: [
     CookieService,