Hi, Stephen.
Sure, this could be accomplished via a CSS media query. However, we do not provide CSS customizations, per our Scope of Support / Terms, because the CSS solution would be different for each user’s site, based on whichever theme and other plugins they may have active at any given time.
You can add custom CSS code via your child theme’s style.css file, via WordPress 4.7’s Customizer CSS settings, or via a third-party plugin (not guaranteed or supported by us), like:
- SiteOrigin CSS (helps you visually build CSS selectors via its Inspector and Visual Editor, if that’ll help you)
- Simple Custom CSS
- Jetpack (supports regular CSS and the LESS and Sass pre-processors)
If you’re not a CSS expert, Jetpack’s Custom Design reference may prove helpful.
If you are struggling to get some CSS to take effect, you’re welcome to share your custom CSS code and also a link to view it in action, and I might be able to help get you over the finish line.
Please let me know how it goes for you.