Add body 100% width for the preview, refactor the modalActivated watcher, use body scroll lock for the setting tab content

src/components/settings_modal/settings_modal.scss

@@ -14,6 +14,10 @@
        * - 50px - leaving tiny amount of space so that titlebar + tiny amount of modal is visible
        */
       transform: translateY(calc(((100vh - 100%) / 2 + 100%) - 50px));
+
+      @media all and (max-width: 800px) {
+        transform: translateY(calc(((100vh - 100%) / 2 + 100%) - 100px));
+      }
     }
   }