<style>

html, body {
height: 100%;
margin: 0
}

@keyframes breath {
0%   { background-size: 100% auto; }
50% { background-size: 140% auto; }
100% { background-size: 100% auto; }
}

#bkg{
width: 100%;
height: 100%;
animation: breath 4s linear infinite;
background: url("https://cdn.pixabay.com/photo/2016/06/05/02/40/call-1436737__340.png") center center no-repeat;
}
</style>

<div id="bkg"></div>