Hi.
Perhaps you have several template styles and you added the code to the wrong template style.
For example, this code also does not work (not determined)

Add the code here /templates/shaper_helix3/css/custom.css instead of adding it to the template style settings.
Code is added in the Custom CSS section from the shaper_helix3 theme, as usual.
Template style settings > Custom CSS field is not best place for code.
Use this field only for small fragments of the code and only in case if you have several template styles and you want to unique them. In all other cases, place your code in custom.css file.