web: mobile improvements

- all buttons now reflect that they're pressed or hovered
- settings feel way better on mobile
- settings header has been completely remade

web/src/components/settings/SettingsTab.svelte

@@ -95,6 +95,7 @@
     @media screen and (max-width: 750px) {
         .settings-tab {
             background: none;
+            padding: 9px;
             --small-padding: 5px;
         }