computation.scss

$rootFontSize: 10; // px

$_ratio: 1 / $rootFontSize; // default 0.1
@function pix2rem($Number) {
  $_computed: round($Number * $_ratio * 1000) / 1000;
  @return #{$_computed}rem;
}

html {
  font: {
    size: #{$rootFontSize}px;
  }
}

.main {
  height: pix2rem(160); // 16rem
}