resources/themes/stylesheets/ext4/default/variables/_layout.scss

   1 $border-layout-ct-background: adjust-color($base-color, $hue: 3.188deg, $saturation: 0.542%, $lightness: 7.843%) !default;
   2
   3 $accordion-header-color: #000 !default;
   4 $accordion-header-background-color: #d9e7f8 !default;
   5 $accordion-header-background-gradient: null !default;