Color names are kind of tricky, in that they may mean different things to different browsers and OSs.
Granted, these two links are for developing an app, not HTML, but it's worth noting that it can be different.
The COLOR_NAME could equal: BLACK, BLUE, CYAN, GRAY (DKGRAY for dark gray and LTGRAY for light gray), GREEN, MAGENTA, RED, WHITE or YELLOW. Mind that you have to use capital letters.
http://android4beginners.com/2013/06/appendix-b-everything-about-colors-in-android/
Don't hard-code system color values in your app. The color values provided below are intended for reference during your app design process. The actual color values may fluctuate from release to release, based on a variety of environmental variables. Always use the API to apply system colors; for developer guidance, see UIColor.
https://developer.apple.com/design/human-interface-guidelines/ios/visual-design/color/
If you want 100% compatibility, stick with RGB values. It's also something to note that HTML/CSS values should be lowercase. You have an uppercase "W", which could be throwing things off. It shouldn't, but it could.
You'll also notice that "white" isn't a named color in either iOS or Android, so it's likely generating a color based on the string. HTML will do this. If you put a word, name, or even a random string where the color name should be, you'll get a color. This could happen because you use the capital "W" when the browser demands lowercase.
Why does HTML think “chucknorris” is a color?