My common SCSS mixins

_mixins.scss

@mixin link($px: 2, $style: solid, $color: white) {
  text-decoration: none;
  border-bottom: $px*1px $style $color;
}

@mixin font-size($font-size: 16) {
  font-size: $font-size*1px;
  font-size: $font-size/16*1rem;
}

@mixin line-height($line-height: 20) {
  line-height: $line-height*1px;
  line-height: $line-height/16*1rem;
}

@mixin margin($t, $r, $b, $l, $container) {
  margin: percentage($t/$container) percentage($r/$container)
          percentage($b/$container) percentage($l/$container);
}

@mixin padding($t, $r, $b, $l, $container) {
  padding: percentage($t/$container) percentage($r/$container)
          percentage($b/$container) percentage($l/$container);
}