does anybody know if the following image could be made in CSS? Light and dark lines could and should be equal width and edges fade in to darker color so that overall background would be dark color (dark blue in this case).
Any help is well appreciated. My google skills didn’t provide any help on this kind of effect, only ‘starburst stickers / badges kind of things’ was found.

No. Sadly, the css3 generated image specs do not include conical/angular gradients (though they might come out in the next revision!) which would be the most likely way to do this using only css. However, you can do this using css+svg. I actually had this svg document sitting around from an experiment I did once:
Set that as your background-image, and set the css
background-size: cover. That’s it. Here’s a fiddle using this image in a data url.