Colours should be defined in the globals.css file. The should be defined as HSL values space seperated, without the hsl() text. e.g.
root: {
...
--muted: 210 40% 96.1%;
...
}
The tailwind utility classes are defined in the tailwind.config.ts file. These should use the format hsl(var(–varName)). e.g.
theme: {
extend: {
colors: {
...
neutral: "hsl(var(--neutral))",
...
}
}
}