Ahh, much more comfortable somber colors. I personally prefer your second example with a more blue-ish hue c:
I recently got into SCSS (another pre-processer for CSS, just like LESS). You can use any of the original CSS features - the extra LESS features just makes some of the more tedious stuff in CSS easier and prettier. In other words, you don't need to learn LESS (i believe) to contribute to this project ^^
That said, learning to use pre-processers is absolutely heaven if you like toying around with CSS yourself - I much prefer SCSS over SASS or LESS since it has a syntax that looks completely like regular CSS. It does take a little to get into, but once you're set up, it's a smooth ride :3