CSS nesting in the browser, and a build step removed

Native nesting reached broad support this year, which removes the main reason a small stylesheet needed a preprocessor.

.card {
  padding: var(--space-m);

  & .title { font-weight: 600; }

  &:hover { background: var(--surface-2); }

  @media (min-width: 40rem) {
    display: grid;
  }
}

The & is required before a type selector in the earliest implementations, which is the incompatibility with preprocessor syntax that catches people porting a file. What is still missing is everything else a preprocessor does — variables were replaced by custom properties years ago, but mixins and functions have no equivalent, so this removes the build step for a plain stylesheet and not for a design system.