Sass Speech Bubble Mixin from http://www.paulund.co.uk/speech-bubble-sass-mixin

speech-bubble-mixin.scss

@mixin speech-bubble($size, $background) {
  background: $background;
  display: inline-block;
  padding: $size;
  position: relative;
  margin-left: $size;

  &:before {
    content: '';
    position: absolute;
    left: -$size;
    top: 50%;
    transform: translateY(-50%);
    -webkit-transform: translateY(-50%);
    border-top: ($size / 2) solid transparent;
    border-right: $size solid $background;
    border-bottom: ($size / 2) solid transparent;
  }
}