nextcloud-server/core/css/ie.scss

#app-sidebar {
	position: fixed !important;
}
#app-content {
	min-width: $navigation-width !important;
	/**
	 * set min height so the container will grow in IE11
	 * https://stackoverflow.com/questions/28627879/flexbox-not-filling-height-in-ie11
	 */
	min-height: calc(100vh - 50px);
}
#app-sidebar.disappear {
	right: -$sidebar-max-width !important;
}