Theme improvements (#822)

* start converting

* small fixes

* reorganize theme files

* cleanup search bar

* increase spacing

* small tweaks

* fix select styles in Chrome

* cleanup menus

* improve button icons

* restore badges

* remove unused classes

* restore some overrides

* restore bookmark form

* add summary outline

* avoid layout shifts

* restore bookmark details

* increase border radius for modals

* improve details modal

* restore reader mode

* restore settings

* cleanup variables

* start with dark theme

* more dark theme...

* more light theme...

* more dark theme...

* add postcss build

* remove sass processor

* update docker build

* fix alt color

* remove endless symbol

* fix tests

* update assets

* remove sass files

* fix docker build

* cleanup spacing

* improve theme

* update test scripts

* update CI workflow

* fix test

bookmarks/templates/settings/nav.html

@@ -10,7 +10,7 @@
         <a href="{% url 'bookmarks:settings.integrations' %}">Integrations</a>
     </li>
     {% if request.user.is_superuser %}
-    <li class="tab-item tooltip tooltip-bottom" data-tooltip="The admin panel provides additional features &#010; such as user management and bulk operations.">
+    <li class="tab-item">
         <a href="{% url 'admin:index' %}" target="_blank">
             <span>Admin</span>
             <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 20 20" fill="currentColor" class="ml-1" style="width: 1.2em; height: 1.2em; vertical-align: -0.2em;">