Stupid simple grid, simplified from http://css-tricks.com/dont-overthink-it-grids/

responsive.css

  * {
  -moz-box-sizing: border-box;
  -webkit-box-sizing: border-box;
  box-sizing: border-box;
}

.grid {
  background: white;
  margin: 0 0 20px 0;
}
.grid:after {
  /* Or @extend clearfix */
  content: "";
  display: table;
  clear: both;
}

@media screen and (min-width: 480px) {
  [class*='col-'] {
    float: left;
    padding-right: 20px;
  }
  .grid [class*='col-']:last-of-type {
    padding-right: 0;
  }

  .col-2-3 {
    width: 66.66%;
  }

  .col-1-3 {
    width: 33.33%;
  }

  .col-1-2 {
    width: 50%;
  }

  .col-1-4 {
    width: 25%;
  }

  .col-1-8 {
    width: 12.5%;
  }

  .module {
    padding: 20px;
    background: #eee;
  }

  /* Opt-in outside padding */
  .grid-pad {
    padding: 20px 0 20px 20px;
  }
  .grid-pad [class*='col-']:last-of-type {
    padding-right: 20px;
  }
}

responsive.min.css

*{-moz-box-sizing:border-box;-webkit-box-sizing:border-box;box-sizing:border-box}.grid{background:#fff;margin:0 0 20px}.grid:after{content:"";display:table;clear:both}@media screen and (min-width:480px){[class*=col-]{float:left;padding-right:20px}.grid [class*=col-]:last-of-type{padding-right:0}.col-2-3{width:66.66%}.col-1-3{width:33.33%}.col-1-2{width:50%}.col-1-4{width:25%}.col-1-8{width:12.5%}.module{padding:20px;background:#eee}.grid-pad{padding:20px 0 20px 20px}.grid-pad [class*=col-]:last-of-type{padding-right:20px}}

stupid-simple-grid.css

* {
  -moz-box-sizing: border-box;
  -webkit-box-sizing: border-box;
  box-sizing: border-box;
}

.grid {
  width: 99%;
  margin-left: auto;
  margin-right: auto;
}
.grid:after {
  /* Or @extend clearfix */
  content: "";
  display: table;
  clear: both;
}

[class*='col-'] {
  float: left;
  padding-right: 20px;
}
.grid [class*='col-']:last-of-type {
  padding-right: 0;
}

.col-2third {
  width: 66.66%;
}

.col-third {
  width: 33.33%;
}

.col-half {
  width: 50%;
}

.col-quarter {
  width: 25%;
}

.col-eighth {
  width: 12.5%;
}

* {
  -moz-box-sizing: border-box;
  -webkit-box-sizing: border-box;
  box-sizing: border-box;
}

.grid {
  width: 99%;
  margin-left: auto;
  margin-right: auto;
}
.grid:after {
  /* Or @extend clearfix */
  content: "";
  display: table;
  clear: both;
}

[class*='col-'] {
  float: left;
  padding-right: 20px;
}
.grid [class*='col-']:last-of-type {
  padding-right: 0;
}

stupid-simple-grid.min.css

*{-moz-box-sizing:border-box;-webkit-box-sizing:border-box;box-sizing:border-box}.grid{width:99%;margin-left:auto;margin-right:auto}.grid:after{content:"";display:table;clear:both}[class*='col-']{float:left;padding-right:20px}.grid [class*='col-']:last-of-type{padding-right:0}.col-2third{width:66.66%}.col-third{width:33.33%}.col-half{width:50%}.col-quarter{width:25%}.col-eighth{width:12.5%}*{-moz-box-sizing:border-box;-webkit-box-sizing:border-box;box-sizing:border-box}.grid{width:99%;margin-left:auto;margin-right:auto}.grid:after{content:"";display:table;clear:both}[class*='col-']{float:left;padding-right:20px}.grid [class*='col-']:last-of-type{padding-right:0}

stupid-simple-grid.scss

@import "compass";
* {
  @include box-sizing(border-box);
}

$pad: 20px;

.grid {
  width: 99%;
  margin-left: auto;
  margin-right: auto;
  
  &:after {
    /* Or @extend clearfix */
    content: "";
    display: table;
    clear: both;
  }
}

[class*='col-'] {
	float: left;
  padding-right: $pad;
  .grid &:last-of-type {
  	padding-right: 0;
  }
}
.col-2third {
	width: 66.66%;
}
.col-third {
	width: 33.33%;
}
.col-half {
	width: 50%;
}
.col-quarter {
	width: 25%;
}
.col-eighth {
	width: 12.5%;
}* {
  @include box-sizing(border-box);
}



.grid {
  width: 99%;
  margin-left: auto;
  margin-right: auto;
  
  &:after {
    /* Or @extend clearfix */
    content: "";
    display: table;
    clear: both;
  }
}

[class*='col-'] {
	float: left;
  padding-right: $pad;
  .grid &:last-of-type {
  	padding-right: 0;
  }
}