Use different bg colors for active/highlight selectize elements in da…

…rk mode

They have different colors in light mode, and it makes sense to highlight
them in dark mode too.

.active is the hovered option, while .highlight is matching-user-input
letters in the option.

share/static/css/elevator-dark/main.css

@@ -457,3 +457,11 @@ body.darkmode.IE11 .ui-icon-circle-triangle-e {
 .darkmode th.collection-as-table svg.fa-sort * {
     color: #777 !important;
 }
+
+.darkmode .selectize-dropdown .highlight {
+    background-color: #7a7d8d !important;
+}
+
+.darkmode .selectize-dropdown .active {
+    background-color: #3a474d !important;
+}