How to choose a color scheme for a website?

Question

css

Guys, I have a slight shift. I did a bunch of projects and there were almost no problems with this, but now something is completely different. Help me choose a scheme for this site)

a folder with an example of a design (Yandex.disk), the one that is lighter is new pen tests)) but somehow it’s not very .. If it doesn’t make it difficult, offer your options, I’ll consider everything. Thank you)

ps please do not offer color adobe and the like, unless of course it is an option where it will automatically apply the color scheme on the site and show in real time how it will be. If there is, I'd be happy to take a look.