OK, after some thorough testing I figured out it was something related to the CSS transforms and/or animations used on the page – when I disabled them all including setting useCSS: false
for the bxSlider script, it all works fine. However, I couldn’t figure out a simple solution until I searched for similar issues and found the following:
https://www.drupal.org/node/1748514
In your case, adding the following on the page:
#main-menu ul,
#main-menu li {
-webkit-transform: translate3d(0px, 0px, 1px);
}
solves the issue in Safari on Windows (and most probably old iPads though I can’t confirm right now).
Cheers!