body {
    min-height: 100vh;
}

header {
    text-align: center;
    font-size: 125px;
}

.btn {
    border: 5px double red;
    border-radius: 15px;
    padding: 5px;
    text-decoration: none;
    color : Red;
    display: inline-block;
    margin: 5px 0;
}

a:hover {
    background: orange;
}

.center {
    display: flex;
    justify-content: center;
}