Theme Breaking Admin Panel Checkboxes

I am using the Vantage Premium theme and it is causing my checkboxes to malfunction. When I click the checkboxes, nothing shows up but, the box is indeed being checked. When I inspect the checkbox element and disable “webkit-appearance: none; the checkboxes work again but only until I refresh. I’m hoping you guys have a fix for this as I have tried a ton of different things!

The page I need help with: [log in to see the link]