The ever evolving styles of the web. With the growing complexity of websites, frameworks becoming the norm and bundlers controlling the output of our production code there is a heck of a lot to learn and keep up with.
Adam Argyle is a great follow on twitter for anyone interested in CSS snippets, topping up your general knowledge and seeing whats on the horizon and being added to browsers.
A Complete Guide to Flexbox - Read/Bookmark - The ultimate guide guide to flexbox. CSS tricks nailed this one and it's one of the best and easiest to understand guides out there
A Complete Guide to Grid - Read/Bookmark - Another great CSS layouts guide from CSS tricks. I find myself referencing this a lot stored some snippets for easy access.
CSS Animations - Watch/Admire - This is where it all started for me and Devtips holds a very dear place in my heart. A lot of it may be outdated but I'm leaving it here for the memories.
Pseudo Class Selectors - Read - Pseudo classed are incredibly powerful things. I use :after and :before all of the time and it often gives a more elegant and readable solution. This article will help you learn about that and more.
Smoother & sharper shadows with layered box-shadows - Read - Create smoother box-shadows with some techniques from Tobias. Philipp Brumm also created this tool inspired by the article. One thing I would love is if it created several box-shadow classes with varying sizes and strengths.
Styling Layout Wrappers In CSS - Read - A comprehensive introduction on creating and styling Layout wrappers. I'm a big fan of this article because it covers a lot of use cases.
Everything I Learned About min(), max(), clamp() In CSS - Read - Ahmed has wrote a great post for those wanting to familiarise themselves with min(), max() and clamp() CSS functions. I'm excited for this addition to the language and it will revolutionise responsive declarations.
Responsively - Responsive Design Previewer - Tweeted by none other than @addyosmani (so it's bound to be good). I've got to say it's absolute bliss being able to see all of the screens I care about in one space side by side, and it even updates if you're using hot reloading.