header a,
header button,
footer a {
    color: inherit;
    text-decoration: none;
    border: none;
    background: none;
    width: auto;
}

    header a:hover,
    .footer a:hover {
        border: inherit;
        background-color: inherit;
    }

a,
button {
    display: block;
    color: black;
    text-decoration: none;
    border: 2px solid black;
    background-color: transparent;
    width: 40%;
    text-align: center;
    margin: 5px 2px;
}

    a:hover,
    button:hover {
        color: black;
        border: 2px solid black;
        background-color: grey;
    }