Dark theme has bright background

[justin-hackin]

I love diagrams and so this generator made me very happy to find. I didn't even notice it had a dark theme at first 😮 that made me even happier 🎉

The color inside the boxes looks great 👍 However, I'm a bit confused about why the background is white. For me, the purpose of the dark theme is to reduce eyestrain from brightness. Some people are sensitive to white screens and go to great lengths to avoid white backgrounds.

Making the background darker than the darkest shade and then making the arrows white would be a great addition to this theme.