SugarSS
Indent-based CSS syntax for PostCSS.
a
  color: blue
.multiline,
.selector
  box-shadow: 1px 0 9px rgba(0, 0, 0, .4),
              1px 0 3px rgba(0, 0, 0, .6)
// Mobile
@media (max-width: 400px)
  .body
    padding: 0 10pxAs any PostCSS custom syntax, SugarSS has source map, stylelint and postcss-sorting support out-of-box.
It was designed to be used with postcss-simple-vars and postcss-nested.
But you can use it with any PostCSS plugins
or use it without any PostCSS plugins.
With postcss-mixins you can use @mixin syntax as in Sass.
Docs
Read full docs here.