server/apps/files/css/mobile.scss

/* 938 = table min-width(688) + app-navigation width: 250
   769 = size where app-navigation (768) is hidden +1
   688 = table min-width */
@media only screen and (max-width: 938px) and (min-width: 769px), only screen and (max-width: 688px) {

.app-files #app-content.dir-drop{
	background-color: rgba(255, 255, 255, 1)!important;
}

/* don’t require a minimum width for files table */
#body-user #filestable {
	min-width: initial !important;
}

/* hide size and date columns */
table th#headerSize,
table td.filesize,
table th#headerDate,
table td.date {
	display: none;
}

/* remove padding to let border bottom fill the whole width*/
table td {
	padding: 0;
}
/* and accordingly fix left margin of file list summary on mobile */
.summary .info {
	margin-left: 105px;
}

/* remove shift for multiselect bar to account for missing navigation */
table.multiselect thead {
	padding-left: 0;
}

/* restrict length of displayed filename to prevent overflow */
table td.filename .nametext {
	width: 100%;
}

#fileList a.action.action-menu img {
	padding-left: 0;
}

#fileList .fileActionsMenu {
	margin-right: 6px;
}
/* hide text of the share action on mobile */
#fileList a.action-share span:not(.icon) {
	display: none !important;
}
#fileList a.action.action-favorite {
	opacity: .7 !important;
}
#fileList a.action.action-favorite {
	opacity: .3 !important;
}

/* ellipsis on file names */
table td.filename .nametext .innernametext {
	max-width: calc(100% - 175px) !important;
}

/* proper notification area for multi line messages */
#notification-container {
	display: -webkit-box;
	display: -moz-box;
	display: -ms-flexbox;
	display: -webkit-flex;
	display: flex;
}

/* shorten elements for mobile */
#uploadprogressbar, #uploadprogressbar .label.inner {
	width: 50px;
}
/* hide desktop-only parts */
#uploadprogressbar .desktop {
	display: none !important;
}
#uploadprogressbar .mobile {
	display: block !important;
}

}