triangle-up.css

.arrow-outter,
.arrow-inner {
  left: 285px;
  border: 8px dashed transparent;
  display: block;
  position: absolute;
  height: 0;
  width: 0;
}
.arrow-inner {
  top: -15px;
  border-bottom: 8px solid #fff;
  font-size: 0;
  line-height: 0;
}
.arrow-outter {
  top: -16px;
  border-bottom: 8px solid #ccc;
  font-size: 0;
  line-height: 0;
}

<span class="arrow-outter"></span>
<span class="arrow-inner"></span>