#error404{
    margin: 20px auto;
    width: 600px;
    height: 600px;
    font-family: Verdana, Geneva, Tahoma, sans-serif;
}
#error404 h1{
    font-size: 26px;
}
#error404 h2{
    font-size: 20px;
}
#error404 p{
    font-size: 16px;
}
#error404 a{
    font-size: 18px;
    text-decoration: none;
    color: blue;
}