Recreator

var webPsupport = (function() {
  var webP = new Image();
  webP.onload = WebP.onerror = function () {
    callback(webP.height == 2);
  };
  webP.src = 'data:image/webp;base64,UklGRjoAAABXRUJQVlA4IC4AAACyAgCdASoCAAIALmk0mk0iIiIiIgBoSygABc6WWgAA/veff/0PP8bA//LwYAAA';
});

document.write(webPsupport ? 'webP supported!' : 'webP not supported.');

this.container = document.querySelector('.container');

button {
aspect-ratio: 1/1
}