Eric Meyer’s CSS books for O’Reilly are unsurprisingly exhaustive. For incremental, hands-on work, try using Codepen to slowly work your way through bounded use

Eric Meyer’s CSS books for O’Reilly are unsurprisingly exhaustive. For incremental, hands-on work, try using Codepen to slowly work your way through bounded use cases (e.g., set up a pen and just work on styling buttons, or flex layout, or transforms); Codepen also lets you use preprocessors like SASS and LESS inline, so it’s a great way to get used to the various quirks of CSS and its toolchains without having to set up entire projects.