[asdfzalsd]

I really like the design. I do a lot of backend dev so I gotta ask, what goes into designing a aesthetically pleasing site like that?

[kemyd]

I created Bullets.tech using my tool https://bootstrapshuffle.com

It's of course based on Bootstrap. I like to use an online builder to experiment with fonts/colors. I found fonts here: https://fontpair.co/

Probably, I changed only the primary color from the default Bootstrap palette. I used one from this palette: https://flatuicolors.com/palette/ca

I'm mostly backend developer like you. I experiment a lot to find something looking good!

[type0]

As aitchnyu allready noticed you might need to think about what fonts you use and where. Josephin Sans could work fine for aside headers but you shouldn't use it all throughout the site if you care about readability.