/*Here yoy can place all you custom css declarations that will overwrite already existing styles or add new ones*/
.grm-media-block .joomla-modal .modal-dialog .modal-content,
.grm-media-block .joomla-modal .modal-dialog .modal-content [class*=jviewport-height] iframe{
    min-height: 400px;
}
.grm-media-block .joomla-modal .modal-dialog .modal-content .modal-header{
    padding-left: 20px;
    padding-right: 20px;
}