Here's one that had me at a loss for a long time that I just figured out. You can easily remove the highlight border (the border that comes up when an element is focused) or change it's color in a WebView with CSS! The WebKit-specific property "-webkit-tap-highlight-color" is what you're looking for.
The following line will disable it on a page completely:
* {
-webkit-tap-highlight-color: rgba(0, 0, 0, 0);
}
rgba() is just like rgb(), but it takes a 4th parameter for opacity. It's my belief that this would probably work for iPhone WebView's as well, since both Chrome and Safari are based off of WebKit.