Add midnight-ocean color scheme support for GTK2/3/4 and Qt5/6

.config/gtk-3.0/colors.css

@@ -0,0 +1,54 @@
+/* midnight-ocean GTK3 overrides */
+
+@define-color theme_bg          rgba(11, 27, 43,   0.98); /* Deep Ocean */
+@define-color theme_fg          rgba(202,211,232,  0.90); /* Sea Foam */
+@define-color theme_selected_bg rgba(79,132,204,   0.30); /* Bubble Fade */
+@define-color theme_hover_bg    rgba(79,132,204,   0.50); /* bg_hover */
+@define-color theme_border      rgba(79,132,204,   0.50); /* border_main */
+@define-color theme_accent      #4F84CC; /* Abyss Accent */
+@define-color theme_warning     #FFCC33; /* Sunken Gold */
+
+/* Base window & text */
+window,
+dialog,
+.view,
+headerbar {
+  background-color: @theme_bg;
+  color: @theme_fg;
+}
+
+/* Selected items */
+* selection,
+.treeview row:selected,
+.list row:selected,
+.button:selected,
+.toggle:selected {
+  background-color: @theme_selected_bg;
+  color: @theme_fg;
+}
+
+/* Hover states */
+* button:hover,
+* entry:hover,
+* switch:hover,
+* scrollbar:hover {
+  background-color: @theme_hover_bg;
+}
+
+/* Borders & accents */
+* {
+  border-color: @theme_border;
+}
+
+/* Focus outlines */
+*:focus {
+  outline-color: @theme_accent;
+}
+
+/* Warnings/errors */
+dialog.error,
+.error message,
+.notification.critical {
+  background-color: @theme_warning;
+  color: @theme_bg;
+}