code: function checkCssSupported() {
    // First, check if the 'perspective' CSS property or a vendor-prefixed
    // variant is available.
    var perspectiveProperty = prefixProperty('perspective');
    var el = document.createElement('div');
    var supported = typeof el.style[perspectiveProperty] !== 'undefined';
  
    // Certain versions of Chrome disable 3D transforms even though the CSS
    // property exists. In those cases, we use the following media query,
    // which only succeeds if the feature is indeed enabled.
    if (supported && perspectiveProperty === 'WebkitPerspective') {
      var id = '__marzipano_test_css3d_support__';
      var st = document.createElement('style');
      st.textContent = '@media(-webkit-transform-3d){#' + id + '{height: 3px;})';
      document.getElementsByTagName('head')[0].appendChild(st);
      el.id = id;
      document.body.appendChild(el);
      // The offsetHeight seems to be different than 3 at some zoom levels on
      // Chrome (and maybe other browsers). Test for > 0 instead.
      supported = el.offsetHeight > 0;
      st.parentNode.removeChild(st);
      el.parentNode.removeChild(el);
    }
  
    return supported;
  }
docs: Detect CSS 3D transforms support. Adapted from Modernizr.