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/styles/theme/tables.css

@@ -0,0 +1,26 @@
+/* Tables */
+.table {
+    border-collapse: collapse;
+    border-spacing: 0;
+    width: 100%;
+    text-align: left;
+
+    /* Scrollable tables */
+
+    &.table-scroll {
+        display: block;
+        overflow-x: auto;
+        padding-bottom: 0.75rem;
+        white-space: nowrap;
+    }
+
+    & td,
+    & th {
+        border-bottom: var(--border-width) solid var(--border-color);
+        padding: var(--unit-3) var(--unit-2);
+    }
+
+    & th {
+        border-bottom-width: var(--border-width-lg);
+    }
+}