Write maintainable CSS with variables, nesting, mixins, modules, maps, and compiled output.
Lessons
Use math, string, color, list, map, and meta.
Built-in Modules is easiest to learn by reading the example, changing it, and observing the result.
@use 'sass:math';
@use 'sass:color';
@use 'sass:map';
$theme: (primary: #4f46e5);
.button {
background: map.get($theme, primary);
padding: math.div(32px, 2);
border-color: color.adjust(map.get($theme, primary), $lightness: -10%);
}Practice the Built-in Modules example in a small scratch file, then explain what changed and why.