.cont:not(.on) {
    display: none;
}

.m {
    display: none;
}

#vr .m a {
    display: block;
}

#materials .tab_list li {
    padding:8px 16px;
}

#materials img {
    margin-top: -1px;
}

#materials .cont {
    height: 700px;
    overflow: auto;
}

@media all and (max-width:780px){
    .pc {
        display: none;
    }

    .m {
        display: block;
    }

    #materials .cont {
        max-width: 90%;
        height: auto;
        margin:0 auto;
    }
}