Improve readability of dark-colored text with outlines

[necessarily-equal]

On another note, I think I've found where the readability problem I'm feeling is coming from: it's when there is a black border around some blue (^4) text or most other cases where the color is close enough to the color of the black outline. Maybe to improve on that we can use white border around these. I think this can be improved on later though.

Maybe we could have Rocket_QuakeToRML add class="darktext" or something like that to spans using a dark foreground color. Then CSS targeting this class could be added.

Originally posted by @slipher in #155 (comment)