.code {
    background: #333;
    color: #fff;
    padding: 20px;
    width: 1000px;
    font-family: 'Courier New', Courier, monospace;
}

.center {
    display: flex;
    justify-content: center;
    align-items: center;
    text-align: center;
    -webkit-text-align: center;
}

li {
    list-style-position: inside;
    text-align: left;
}

.hidden {
    display: none;
    -webkit-display: none;
    -moz-display: none;
    -ms-display: none;
}

a {
    color: #fff;
    text-decoration: none;
}