min-viewport-size.html

<meta name="viewport" content="width=device-width,initial-scale=1,shrink-to-fit=no" id="meta-viewport">
<script>
  !function() {
    var viewport = document.getElementById('meta-viewport');
    function onResize () {
      var value = window.outerWidth < 375 ? "width=375" : "width=device-width,initial-scale=1,shrink-to-fit=no";
      if (viewport.getAttribute('content') !== value) {
        viewport.setAttribute('content', value);
      }
    }
    addEventListener('resize', onResize, false);
    onResize()
  }();
</script>