.arrow-up {
  width: 0;
  height: 0;
  border-left: 5px solid transparent;
  border-right: 5px solid transparent;

  border-bottom: 5px solid black;
}

.arrow-down {
  width: 0;
  height: 0;
  border-left: 20px solid transparent;
  border-right: 20px solid transparent;

  border-top: 20px solid #f00;
}

.arrow-right {
  width: 0;
  height: 0;
  border-top: 60px solid transparent;
  border-bottom: 60px solid transparent;

  border-left: 60px solid green;
}

.arrow-left {
  width: 0;
  height: 0;
  border-top: 10px solid transparent;
  border-bottom: 10px solid transparent;

  border-right:10px solid blue;
}