When you’re designing content for your site, you should design primarily for desktop screens, then use CSS to adjust what’s on mobile.

This statement is false because modern web design best practices emphasize a mobile-first approach. Designing for mobile screens first ensures that the core content and functionality are prioritized for smaller viewports, which are increasingly common for web access. Then, you progressively enhance the design for larger screens (tablets and desktops) using CSS media queries. This approach guarantees a better user experience across all devices, as opposed to trying to adapt a complex desktop design down to a mobile screen, which often leads to compromises and poor performance.