body{
min-width: 650px;
}
<meta name="viewport" content="width=device-width" id="viewportVal">
<script>
window.onload = function () {
if(screen.width <= 650) {
var vp = document.getElementById('viewportVal');
vp.setAttribute('content','width=650');
}
}
</script>
@media (max-width:650px){
html{
width: 100%;
height: 100%;
overflow-x: hidden;
}
body{
min-width:650px;
overflow:auto;
}
}