Hit and miss colors too similar

[diegosouza]

Hello people,

First of all, nice project. No doubt it helps the Elixir community a lot.

I've been using the HTML coverage. It's really hard to me to distinguish the hit and miss colors. I thought it was because of some color blindness I have.

So I asked for my wife to have a look. She has a perfect vision but she also considered the colors too similar. It gets even worse depending on the screen quality, calibration and the angle we look to.

I've compared the coveralls.io colors and the excoveralls colors. Can you easily spot the 4 colors?

|      | coveralls             | excoveralls         |
| hit  | rgba(208,233,153,0.2) | rgba(95,151,68,0.2) |
| miss | rgba(216,134,123,0.2) | rgba(185,73,71,0.2) |

I'd like to suggest to follow coveralls.io colors, or at least, an increment to the alpha number, from 0.2 to 0.4.

If you think it interesting, I can send the PR.

[carloswimmer]

Since these colors are exactly the problem of red-green color blindness (see types of color blindness), I believe these changes can already help many people who has this vision particularity in small intensities, but there are more things that can be done to avoid this uncomfortable situation for some users:

• a button to turn on high contrast where one color would be light with black text and the other would be dark with white text
• an yellow icon ⚠ on missed lines

[carloswimmer]

Or, in a cleaner way:

[diegosouza]

Or, in a cleaner way:

This approach would help too.
Your suggestion (with an image or emoji) is better than the builtin coverage for Elixir: