@media only screen and (max-width: 768px) {
    .ui.legacy.modal, .ui.legacy.page.dimmer > .ui.modal{
        top:5%;
        margin-top:0!important;
    }

    .ui.modal .ui.dropdown .menu {
        max-height: 200px !important;
        overflow-y: auto !important;
        -webkit-overflow-scrolling: touch !important;
        overscroll-behavior: contain !important;
        touch-action: pan-y !important;
        z-index: 99999 !important;
    }
}