Features that a design tool should support natively.
A responsive menu with the same HTML for all viewports.
Natural gradients and box shadows with easing effects.
Browsers can do so much more for front-end developers.
Why a website needs 3 states for its dark mode implementation.
How they work, which ones are there, and which ones you should use.
Bootstrap, Foundation, Material UI, Tailwind CSS, and others.
Copy over the examples and make them your own.