cheatsheet for common used but confusing css properties and features.

css_confusing_features_tips.md

1. what does CSS selector with space and comma separate mean?

• for space, it apply one rule to multi-selectors.
• for comma, it apply the next selector's rules only one the context of previous selectors.
• Details answer: http://stackoverflow.com/questions/3344284/what-do-commas-and-spaces-in-multiple-classes-mean-in-css