[Theme Horse Support Team]

Hello,

CSS selector need to be specific rather than global. Just try below custom CSS:

@media only screen and (min-width: 768px) {
	.single.full-width-layout .site-main .entry-content p,
	.single.full-width-layout .site-main .entry-content ul li {
		max-width: 700px;
		margin: auto;
		font-family: ‘Open Sans’, sans-serif;
		color: #000;
		text-align: left;
		font-size: 16px;
		line-height: 28px;
		width: 700px;
		font-weight: 300;
		font-style: normal;
	}
}

Thank you!