Using background image

My background image is not showing with a fixed height.

My code is as follows

<div class=”site-branding”>
<div class=”main-image”>
</div>
</div>

and css

.main-image{
background-image: url(‘/nonprofit/wp-content/uploads/2015/04/image1.jpg’);
background: url(‘image1.jpg’);
background-position: center;
background-size: cover;
background-repeat: no-repeat;
}

is there a solution to get this working without a fixed height?