The site has a bit of Webkit-only CSS. Tip: don't use bleeding edge CSS like appearance, and if you do, at least test it in Chrome, Edge, and Firefox. You can

The site has a bit of Webkit-only CSS. Tip: don't use bleeding edge CSS like appearance, and if you do, at least test it in Chrome, Edge, and Firefox. You can fix the broken CSS for Firefox by adding -moz-appearance in addition to -webkit-appearance. https://developer.mozilla.org/en-US/docs/Web/CSS/-moz-appearance https://developer.mozilla.org/en-US/docs/Web/CSS/-moz-appear...