build(app): use sass colors

assets/settings/_colors.scss

@@ -0,0 +1,14 @@
+/* **************************************************************************
+   SETTINGS > COLORS
+   To get the color name: http://veli.ee/colorpedia/?c=354052
+   ************************************************************************** */
+
+// Black
+$black: #000000;
+$ebony-clay: #273142;
+$mirage: #1b2431;
+$mirage2: #171e29;
+$oxford-blue: #313d4f;
+
+// White
+$white: #ffffff;