body  font-size 16px  .header    height 40px    #nav      padding-bottom 10px

To yield:

body {
  font-size: 16px;
}
body .header {
  height: 40px;
}
body .header #nav {
  padding-bottom: 10px;
}

headHeight = 20%$headWidth = 1000pxbody  height 100% - headHeight  header    width $headWidth*1.08

body {  height: 80%;}body header {
  width: 1080px;
}

clearfix(el, other)
  {el}::after
    overflow hidden
    other(1px,solid,lighten(red, 60%))
border(args...)
  border-bottom args
clearfix('.content', border)

.content::after {
  overflow: hidden;
  border-bottom: 1px solid #f99;
}

red(#c00)// => 204light(#eee)// => truelightness(#e70)// => 46.66666666666%width = 960px 1080px 1280pxpush(width, 1440px, 1920px)
// width => 960px 1080px 1280px 1440px 1920px
unit(15%, 'px')
// => 15px
base-convert(1811208624,36)// => tychio

@import "reset"

@import reset