@media only screen and (max-width: 600px) {
    ul.navbar-nav li{padding:5px;margin-bottom:0;text-align:center}
    a.nav-link.ds-btn { margin-left: 0;display: inline-block;}
    img.iith-logo {height: 40px;}
    div#collapsefourty iframe {height: 850px;width: 100%;}
}
@media only screen and (min-device-width :768px) and (max-device-width :1024px) and (orientation :portrait) {
    ul.navbar-nav li{padding:5px;margin-bottom:0;text-align:center}
    a.nav-link.ds-btn { margin-left: 0;display: inline-block;}
}
@media only screen and (max-device-width:1366px) and (min-device-width:1024px) and (orientation:portrait) {
    ul.navbar-nav li{padding:0px;margin-bottom:0;text-align:center}
    a.nav-link.ds-btn { margin-left: 0;display: inline-block;}
    img.iith-logo {height: 40px;margin: 2px;}
    ul.navbar-nav li.nav-item a {font-size: 14px;}
}