Simple FSCSS example

/*===variables===*/

$init-border: 2px groove;

$init-box-size: 300px;

$page-color: #123456;

$page-bg-color: #654321;

$font-stack: normal 18px/12px sans-serif;

$init-gradient: radial-gradient(circle at 100% mx(,123,234,345,456,567,",#000")), radial-gradient(circle at 10% mx(,123,234,345,456,567,",#000"));

body{

  text-align: center;

  padding: 5%;

  color: $page-color;

  font: $font-stack!;

  -*-text-stroke:1px #f99;

}

.body{

  border: $init-border! #459;

  /*===assign value to width and height===*/

  %2(width,height[:$init-box-size;])

  display: flex;

  overflow: hidden;

  background:

  radial-gradient(ellipse at top, #000567, transparent),

  radial-gradient(ellipse at bottom, #000234, transparent);
Border-radius: 2%;
}

/*=== replace ===*/

re(boxSize:"%4(width,height,min-width,min-height[:70px;]);")

re(padding:"padding-")

re(backgroundB:"background-B")

re(lendM:"lend-M")

re(borderB:"border-B")

.body $(class^:div){

  boxSize

  paddingTop: 60px;

  background: $init-gradient!;

  backgroundBlendMode: lighten;

  borderBottom: $init-border! #459;

}