Less mixin for v-centering

vcenter.less

/* A less mixin for vertical centering
 * Consider a parent div with { height: 70px, position: relative }
 *
 * Case 1: Text div with no height
 * .textdiv {
 *   .v-center(70px, text) //where 70px is parent div height
 *  }
 *
 * Case 2: Div with it's own height (uses absolute positioning)
 * .nontextdiv {
 *   .v-center(30px) //where 30px is the height of the child div
 *  }
 *
 */
.v-center (@parent_h: 50px, text) {
  line-height: @parent_h;
}
.v-center (@h: 20px) {
  position: absolute;
  height: @h; 
  margin-top: @h * -0.5;
  top: 50%;
}