body {
    background-color: #f4f4f4;
    margin: 0;
    padding: 0;
    color: #222;
}
a {
    color: #222;
    background-color: #fff;
    padding: 30px 30px;
    border-radius: 10px;
    box-shadow: 0 0 4px rgba(0, 0, 0, .2);
    transition: all 300ms linear;
}
a:hover {
    background-color: #ffd400;
    color: #222;
    text-decoration: none;
    cursor: pointer;
}
.center {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
}