css:

.status-bar {
  margin: 0;
  padding: 0;
  list-style: none;
  display: table;
  width: 800px;
  border-radius: 1px;
  overflow: hidden;
}
.status-bar li {
  background: #656565;
  display: table-cell;
  height: 30px;
  line-height: 30px;
  text-align: center;
  color: #fff;
  position: relative;
}
.status-bar li .triangle-right-bg {
  display: inline-block;
  width: 0px;
  height: 0px;
  border-style: solid;
  position: absolute;
  z-index: 1;
  border-width: 18px;
  right: -36px;
  border-color: transparent transparent transparent #444;
  top: -3px;
}
.status-bar li .triangle-right {
  display: inline-block;
  width: 0px;
  height: 0px;
  border-style: solid;
  border-width: 15px;
  position: absolute;
  right: -30px;
  z-index: 1;
  border-color: transparent transparent transparent #656565;
}
.status-bar li.checked {
  background: #779900;
}
.status-bar li.checked .triangle-right {
  border-color: transparent transparent transparent #779900;
}

html:

<ul class="status-bar">
        <li class="checked">
            第一步
            <i class="triangle-right-bg"></i>
            <i class="triangle-right"></i>
        </li>
        <li>
            第二步
            <i class="triangle-right-bg"></i>
            <i class="triangle-right"></i>
        </li>
        <li>
            第三步
        </li>
    </ul>