All selectors are assigned a weight, and the heaviest selector takes precedence when conflicting CSS rules exist. It's natural when architecting a website that you have general styles that get overridden with more specific styles in different circumstances. In the global area at the top of the style sheet, a very broad style has been set for all paragraph elements:
p { font-size: 16px; line-height: 1.6; margin-bottom: 20px;}
The font size is 16px. There is a line-height property of 1.6 and 20px of margin-bottom. Naturally, I might want to overwrite either line-height or margin-bottom under varying circumstances. Let's try and override that with a new rule set with a selector of .content-block p:
p { font-size: ...
