Track for the Context slider not visible in dark mode

[arouanet]

Thank you for your work adapting GitX to dark mode. It has been very reliable for me so far.

A small issue I just noticed: in the Stage view, the track for the Context slider is almost the same color as the surrounding background, making it nearly invisible.

As range input types are not very easy to style in CSS, the simplest way I found to fix the problem is to change the title background color to a slightly lighter color in commit.css, e.g.:

#title {
	...
	background-color: #34312C;
	...
}