Never Use Black (2012)
I have a design background and have written a lot of CSS, and I have opinions so just interpret this all as a personal preference if you want.* It's basic floor/ceiling stuff. Once you go #000000, you can't go any darker. Are you 100% sure the thing you're making #000000 is the absolute darkest thing on your site/app you'll ever need to declare?* Conversely, never use white! Modern macOS sucks at this! A large window of Mail.app in light mode is pretty blinding. What if you want to add a subtle highlight to a button border on a white background? #fafafa was always a go-to white for me because its easy to remember.* Shadows are really never black and your CSS shadows will look better if you don't default to black. Toggle 'tint shadows' on the _excellent_ css shadow palette generator: https://www.joshwcomeau.com/shadow-palette/. Play with background colors, you'll see.* Your design will never please everyone, especially anything close to a majority on certain tech news aggregators.