Thread:Flanqer/@comment-26828130-20190723115450/@comment-24931587-20190731165744

IE11 shouldn't have any problems with the CSS you're using for the tooltips; background, border, and color have been supported since IE4. Javascript is probably disabled or blocked on his work computer for security reasons.

BTW, get rid of ALL the "!important" tags in your CSS. "!important" is rarely needed, and usually just creates bigger problems later. It's often recommended by people who don't understand what it actually does. In almost all cases, the correct solution is to make the CSS selector more specific. See this article for an explanation of why "!important" should be avoided.