html, body{ margin: 5px; padding: 5px; }
#main_container{
    width: 800px;
    margin: auto;
    margin-top: 5px;
    margin-bottom: 5px;
    h1, h2, h3, h4, h5, h6, p {margin: 6px 0;}
    h1 {color: black;}
}
@media (max-width: 810px) {
    #main_container{
        width: 100%;
        margin: 5px;
    }
}