<style>
  #hint {
    background-color: rgba(0, 0, 0, 0.75);
    height: 30px;
    position: relative;
    width: 100px;
    border-radius: 2px;
    text-align: center;
    line-height: 30px;
    color: #ffffff;
    font-family: 'Arial', san-serif;
    font-size: 12px;
  }
  
  #hint:after {
    content: ' ';
    position: absolute;
    width: 0px;
    height: 0px;
    left: 50%;
    top: 100%;
    margin-left: -5px;
    border: 5px solid transparent;
    border-top-color: rgba(0, 0, 0, 0.75);
  }
</style>
<div id="hint">Sample text</div>