html
{
    background-color: grey;
    width: 100%;
    height: 100%;
}
#main
{
    font-size: 30px;
    margin: auto;
    padding: 2px;
    height: auto;
    overflow: auto;
    display: grid;
    grid-template-areas:
        "log"
        "pas"
        "err";
}
#login
{
    grid-area: log;
}
#pass
{
    grid-area: pas;
}
#error
{
    grid-area: err;
}

@media (min-width: 900px)
{
    #main
    {
        width: 30%;
    }
    #login
    {
        width: 10%;
        margin: auto auto auto 30%;
        grid-area: log;
    }
    #pass
    {
        width: 10%;
        margin: auto auto auto 30%;
        grid-area: pas;
    }
}
@media (max-width: 900px)
{
    #main
    {
        width: 90%;
    }
    #login
    {
        width: 90%;
        margin: auto auto auto 20%;
        grid-area: log;
    }
    #pass
    {
        width: 90%;
        margin: auto auto auto 20%;
        grid-area: pas;
    }
}