Ask HN: CSS for developers

Hello, I am an experienced (full stack) developer however I always struggle when it comes to playing with CSS. When there's a CSS guy (designer) available everything is smooth, however if I need to do even simple things with CSS I struggle for much time and resort to trial and error and probably hacky solutions.

Most of my projects just use the stock Bootstrap without any changes; if something (even something small) needs to change then my nightmare begins :( Also, in various projects I need to work with non-CSS designers (i.e people that create the site in photoshop or something similar) and then I need to replicate that design (from a bunch of images) to CSS; this is a huge PITA for me and usually I just avoid such projects.

Now, I believe I am familiar with the basics of CSS (selectors, box model, display, positioning, floats, responsive etc) however I can't undestand the whole picture.

What I would like to be able to do is replicate as faithfully as possible (I mean replicate with CSS) an existing site starting from scratch, i.e just with an empty index.html and my own css (let's forget bootstrap for now) plus maybe a basic reset-stylesheet. Is there a book I should read for learning this? Is there some on-line course/tutorial? Something else that you recommend? Maybe a framework? This mainly has to do with laying out things, having proper classes to reuse styles and being responsive, I don't care that much about colors, shadows, borders, fonts, etc since they can easily be copied over.

Thanks !