A simple, but effective CSS boilerplate. This assumes you have some kind of reset/normalize going on as well.

boiler.css

html { 
  font-size: 12px ; 
  font-family: 'Open Sans', sans-serif;
}

div { 
  position: relative;
  box-sizing: border-box;
}

.absolute { position: absolute; }
.middle { vertical-align: middle; }
.inline { display: inline-block; }
.nowrap { white-space: nowrap; }
.column { float: left; }
.padded { padding: 1.5em; }
.full-width { width: 100%; }
.full-height { height: 100%; }
.text-center { text-align: center; }
.text-right { text-align: right; }
.btn { cursor: pointer; }
.small { font-size: 0.75em; }
.rounded { border-radius: 0.4rem; }
.hidden { display: none; }
.left { float: left; }
.right { float: right; }
.fa { min-width: 1em; }

.clearfix {
  content: "";
  display: table;
  clear: both;
}

.animated, .animated * {
  transition-property: background, color, font-size, box-shadow, width, height;
  transition-duration: 0.2s;
}

/* Media object */
.flexible, .flexible-body {
  overflow:hidden;
  _overflow:visible;
  zoom:1;
}