Make input boxes clearly visible

Some input boxes blend into the background in Browsh so well, that they can't immediately be seen by the user.

Additionally this prevents the caret in caret mode of the vim like key navigation I'm implementing from being able to stop at some input boxes.

Examples of this input box invisibility can be seen on google and google news.

This probably can be fixed by injecting CSS styles to ensure that input boxes are colored differently from their background.