Tailwind CSS

Tailwind CSS v4 is on when the page CSS starts with @import "tailwindcss", which new projects do unless you untick it. Classes are compiled as you type, in HTML and in JSX.

Your own colours#

Colour tokens become classes too. This page CSS gives you bg-brand and text-ink:

:root { --brand: #1b6c80; --ink: #16181d; }

@theme inline {
--color-brand: var(--brand);
--color-ink: var(--ink);
}