Sass Mixin toolbox

_tools.scss

// ----
// Sass (v3.3.0.rc.1)
// Compass (v0.13.alpha.10)
// ----

/* convert font-size in px into rem with a px fallback */
$main-font-size : 10;

@mixin font-size($sizeValue: 10) {
  font-size: $sizeValue + px;
  font-size: calculateRem($sizeValue);
}

@function calculateRem($size) {
  $remSize: $size / $main-font-size;
  @return #{$remSize}rem;
}

/* create line-height from font-size and line height in same unit */
@mixin line-height($fontsize, $lineHeight){
    line-height: $lineHeight/$fontsize; 
}

/* add prefix for calc function and use fall back if needed */
@mixin calc($property, $expression, $default :"") {
  @if $default !="" {
    #{$property}: #{$default};
  }
  #{$property}: -moz-calc(#{$expression});
  // #{$property}: -o-calc(#{$expression});
  #{$property}: -webkit-calc(#{$expression});
  #{$property}: calc(#{$expression});
}

SassMeister-output.css

/* convert font-size in px into rem with a px fallback */
/* create line-height from font-size and line height in same unit */
/* add prefix for calc function and use fall back if needed */