Module:Gallery/styles.css

.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;
}

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