<a href="/" class="bn4">Button</a>
.bn4 {
background-color: #ffffff;
border: none;
color: rgb(0, 0, 0);
padding: 0.7em 1.7em;
text-align: center;
font-size: 16px;
margin: 4px 2px;
opacity: 0.6;
transition: 0.3s;
display: inline-block;
text-decoration: none;
cursor: pointer;
}
.bn4:hover {
opacity: 1;
}