style.css

@media only screen and (max-width: 767px) {
	.five-sixths,
	.four-fifths,
	.four-sixths,
	.one-fourth,
	.one-half,
	.one-fifth,
	.one-sixth,
	.one-third,
	.three-fifths,
	.three-fourths,
	.three-sixths,
	.two-fifths,
	.two-fourths,
	.two-sixths,
	.two-thirds {
		margin: 0;
		width: 100%;
	}
}