<a href="/" class="bn1">Button</a>

.bn1 {
  display: inline-block;
  padding: 0.6em 1.7em;
  border: 0.1em solid #ffffff;
  margin: 0 0.3em 0.3em 0;
  border-radius: 0.12em;
  box-sizing: border-box;
  text-decoration: none;
  font-family: "Roboto", sans-serif;
  font-weight: 300;
  color: #ffffff;
  text-align: center;
  transition: all 0.2s;
}

.bn1:hover {
  color: #000000;
  background-color: #ffffff;
}