refactor(common): gc common.scss, organize styles in proper places

public/views/preferencesDeleteWallet.html

@@ -5,13 +5,13 @@
     </ion-nav-back-button>
   </ion-nav-bar>
   <ion-content>
-    <div class="white-bg padding">
+    <div class="padding">
       <h1 class="text-center assertive" translate>Warning!</h2>
       <div class="padding text-center">
         <p translate>
           Permanently delete this wallet.
         </p>
-        <p translate class="bold-text">
+        <p translate>
           THIS ACTION CANNOT BE REVERSED
         </p>
       </div>