Edit on
<a href="#" class="button red">Nút đỏ</a>
<a href="#" class="button blue">Nút xanh</a>
<a href="#" class="button green">Nút xanh lá</a>
.button {
  padding: 5px 10px;
  text-decoration: none;
  margin: 0 1em;
  color: #fff;
}
.button.red {
  background: red;
}
.button.blue {
  background: blue;
}
.button.green {
  background: green;
}
Rerun