Image по ширине - Вопросы по CSS

img{
    max-width: 100%;
}

<a class="img-link" href="/" style="background-image:url('/images/gl.png')"></a>

.img-link
{
	display: block;
	max-height: 500px;
	background-repeat: no-repeat;
	background-position: center center;
	background-size: cover;
}

.img-link img
{
	opacity: 0;
	visibility: hidden;
}