SubNavigation: increase Back button size, constrain message width

app/styles/navigation.scss

@@ -156,19 +156,24 @@
     justify-content: center;
     color: var(--primary-text-color);
     opacity: 0.6;
+    font-size: 16px;
 
     .svg-icon {
       margin-right: 7px;
-      width: 22px;
-      height: 22px;
+      width: 26px;
+      height: 26px;
     }
   }
 
   &__message {
     position: absolute;
+    padding: 0 10px;
     align-self: center;
     justify-self: center;
     font-weight: bold;
+    overflow-x: hidden;
+    text-overflow: ellipsis;
+    max-width: calc(100vw - 200px);
   }
 
   &__cog {