I use this daily, its the web developer toolbar for firefox..

https://addons.mozilla.org/firefox/60/

it lets you do all sorts of cool stuff with your css,

Make sure you use a standards compliant doctype, like xhtml 1.0 strict or transition, and know the difference, like how you can’t use certain css attributes in certain elements..

i don’t know how I managed, but i somehow know much (most, but not all) of the css attributes, and their syntax…i guess since i’m a webdeveloper it just sticks..hmm…anyway, i still keep a reference book, i Have the Sam’s teach yourself in 10 minutes. Its pretty easy to flipthrough and lets you jump around…also w3schools.com has alot of helpful tutorials.