Fixed custom css

(cherry picked from commit bab3437a1feefc49213e1e787db0451491aca9b9)

_includes/css/just-the-docs.scss

 @import "./support/support";
 @import "./color_schemes/{{ include.color_scheme }}";
 @import "./modules";
+@import "./custom/custom";

_sass/modules.scss

@@ -17,4 +17,3 @@
 @import "./tables";
 @import "./code";
 @import "./utilities/utilities";
-@import "./custom/custom";