* { /* everything */
    font-family: system-ui;
}

body {
    background-color: azure;
}

a.button {
    /* text */
    text-decoration: none;

    /* colors */
    color: #000000;
    background-color: #ffffff;
    border-color: #000000;

    /* shape */
    padding: 0 10px 0 10px;
    margin: 0 5px 0 5px;
    border-style: solid;
    border-width: 2px;
    border-radius: 7px;
}

a.button:hover {
    transition: 0.4s;
    color: #ffffff;
    background-color: #000000;
}