If you want to add your own CSS styling to the theme you can either add your code to the Aardvark Child theme style.css file or from Aardvark > Theme Options > Styling > CSS Code.
In both cases your CSS is loaded after the parent theme’s CSS so it will overwrite the parent theme styling. In some cases this may not happen if you’re using less specificity or the original CSS you’re trying to overwrite is coming from a plugin that is being loaded after your custom CSS code.
In these cases try using greater specificity in your CSS, such as prefixing it with “.gp-theme”:
.gp-theme #gp-side-menu-nav .menu-item a { padding: 5px; background: #000; }
If this does not work add “!important” at the end of each attribute:
.gp-theme #gp-side-menu-nav .menu-item a { padding: 5px !important; background: #000 !important; }