Module:Gallery/styles.css

@media all and ( max-width: 720px ) {
	.mw-module-gallery {
	/* Override inline styles in Module:Gallery. !important can be removed when Module:Gallery no longer has them*/
		display: block !important;
		float: none !important;
	}
	.mw-module-gallery div {
		display: inherit !important;
		float: none !important;
		width: auto !important;
	}
}

@media all and ( min-width: 720px ) {
	.mw-module-gallery {
		display: table !important;
		float: right !important;
	}
}