Simple SASS boilerplate (mixins and variables)

mixins.scss

//Border
@mixin border($side:false, $color:$grey-light){
  @if $side {
    border-#{$side}: $border-style $border-width $color;
  } @else {
    border: $border-style $border-width $color;
  }
}

//Prefix property
@mixin prefix($property, $value){
	-webkit-#{$property}: $value;
	-moz-#{$property}: $value;
	-o-#{$property}: $value;
	-ms-#{$property}: $value;
	#{$property}: $value;
}

//Transition
@mixin transition($property, $duration:$transition-duration, $timing:$transition-timing,  $delay:0s){
	@include prefix(transition, $property $duration $timing $delay);
}

//Animations
@mixin animation($name, $seconds, $delay:0s){
	@include prefix(animation, $name $seconds infinite alternate $delay);
}

@mixin keyframes($name){
	@-webkit-keyframes $name {
	  @content;
	}
	@-moz-keyframes $name {
	  @content;
	}
	@-o-keyframes $name {
	  @content;
	}
	@keyframes $name {
	  @content;
	}
}

//Transforms
@mixin transform($value){
	@include prefix(transform, $value);
}

variables.scss

$main-container-width: 960px;


//COLORS
$bg-color: #f5f5f5;

$base-color: #484848;
$base-color-light: lighten($base-color, 30%);

$white: #fff;

$accent: #3796cf;
$accent-dark: darken($accent, 20%);
$accent-hover: darken($accent, 5%);

$accent-alt: #4648ae;
$accent-alt-dark: darken($accent-alt, 20%);
$accent-alt-hover: darken($accent-alt, 5%);

$grey: #d9d9d9;
$grey-light: #f1f1f1;


//TYPOGRAPHY
$main-family: 'Source Sans Pro', Helvetica, Arial, sans-serif;

$main-weight: 300;
$bold-weight: 500;

$line-height: 1.5em;
$line-height-alt: 1.2em;

$size-xs: 0.5em;
$size-s: 0.85em;
$size-m: 16px;
$size-l: 1.1em;


//SPACING
$margin-xs: 5px;
$margin-s: 10px;
$margin-m: 20px;
$margin-l: 40px;
$margin-xl: 80px;

$padding-s: $margin-s $margin-s+5;
$padding-m: $margin-m;
$padding-l: $margin-m+10px $margin-l;


//BORDERS
$border-style: solid;
$border-width: 1px;
$border-width-alt: 2px;
$border-radius: 0;


//ANIMATIONS
$transition-duration: .3s;
$transition-duration-alt: .1s;
$transition-timing: ease;


//ELEMENTS
$header-height: 74px;
$sidebar-width: 250px;