Making that configuration change immediately got IE11 to start rendering the page properly. The solution was to disable IE11’s Compatibility View for intranet sites by doing Setting (gear icon) > Compatibility View Settings > uncheck “Display intranet sites in Compatibility View” checkbox. (Oddly, my IE11 was not using Compatibility View to render another copy of the form that I was trying to use to debug the issue that I had IE loading via the “localhost” domain, which had me confused for a while.) IE11 was rendering the form (running on my local IIS) with its legacy “Compatibility View” engine, which it is by default configured to do for intranet sites. In fact, that did turn out to be exactly the problem. It seemed almost as though IE11 was behaving like a legacy browser that didn’t recognize that newer CSS property. When I looked at the CSS styles in use on the page in IE11’s built-in F12 developer tools, I noticed that the border-radius property on my form’s enclosing div was present, but it was missing its enable/disable checkbox, and the name of the style was shown with a red squiggle underline, as though IE didn’t recognize it. All the icons in the icon libraries of NativeBase, are scalable vector icons that can be customized in terms of size, color, etc. In case if you want to include icon with custom color, size etc then that should go into style. Obviously, these are valid rules so referencing this article by John Schneider Icon can take any two of the following attributes: name, ios, android. Internet Explorer 10 and 11 use a squiggly red underline to indicate invalid rules.