That's a great question. Changing the CSS for mobile would require adding a media query into your theme's CSS file that targets screen sizes that are mobile width.
If you're interested in creating mobile-friendly page content without needing to code, our app Shogun Page Builder lets you design content for all screen sizes. All of the elements in Shogun are responsive by default, which means they'll naturally scale to fit any device. Our Columns element also has options that let you control how the content is arranged on mobile.
Here's an example of how those side-by-side buttons can be quickly recreated in the Shogun editor:
In addition to responsive content, we have a Screen Settings feature that makes it possible to display alternative designs specifically for mobile, tablet, laptop, and widescreen.
If you're interested in testing our app, we have a 10-day free trial. You can uninstall at any time.
Our support team is also available 24/7 to provide assistance. Please feel free to reach out with any additional questions. :)