<section class="container first-image-container"></section>
<section class="container another-image-container"></section>

:root{
	--imageBg: url("https://image.ibb.co/mHzNyL/pexels-photo-255379.jpg") no-repeat;
}
.container,.another-image-container{
	height: 200px;
	width: 300px;
	margin: 10px auto;
}
.first-image-container{
	background: var(--imageBg);
}
.another-image-container{
	--imageBg: url("https://image.ibb.co/fPLArV/2.jpg") no-repeat;
	background: var(--imageBg);
}