Low-contrast/busy background on homepage

Created by: sqs

The new starry universe background looks great overall, but it is too low-contrast/busy IMO with respect to the text. It is a bit hard to read, and it looks like a mistake/oversight.

The 2 red arrows are:

• The Sourcegraph logo mark is hard to see because it is right on top of a white cluster of stars on my monitor. If I make my window narrower, this is no longer a problem, but the white cluster of stars makes some other text harder to read instead.
• The "Enter work email" field is low-constrast with the background.