The greater sign ( > ) selector in CSS means that the selector on the right is a direct descendant / child of whatever is on the left. An example: ... Means only style a paragraph that comes after an article.
So is this @ symbol something new in CSS3, or something old that I've somehow overlooked? Is this something like where with an ID you use #, and with a class you use .? Google didn't give me any good articles related to this. What is the purpose of the @ symbol in CSS?
What is the purpose of the '@' symbol in CSS? - Stack Overflow
The CSS that you referenced is very useful to a web-designer for debugging page layout problems. I often drop it into the page temporarily so I can see the size of all the page elements and track down, for example, the one that has too much padding which is nudging other elements out of place.
What does an asterisk (*) do in a CSS selector? - Stack Overflow
In CSS what is the difference between "." and - Stack Overflow
The first, known as SCSS (Sassy CSS) and used throughout this reference, is an extension of the syntax of CSS. This means that every valid CSS stylesheet is a valid SCSS file with the same meaning. This syntax is enhanced with the Sass features described below. Files using this syntax have the .scss extension.
html - What does the '$' in CSS mean? - Stack Overflow