classes-to-styles.html

<div class="margin-50 padding-50 background-red color-green">Hello</div>

<script>
  var tag = document.querySelectorAll('div')

  for (i=0; i<tag.length; i++) {
    var classes = tag[i].classList
    for (c=0; c<classes.length; c++) {
      var property = classes[c].split('-')[0]
      var unit = classes[c].split('-')[1]
      unit = parseInt(unit) ? unit+'px' : unit

      tag[i].style[property] = unit
    }
  }
</script>