For instance, if a class defines a width of 100 pixels, all DIVS referencing that class will be 100 pixels wide. You can override a DIV's CSS class definition by updating the DIV's HTML code.

Simplest tip ever: Use Visual Studio's Go To Definition with CSS classes to get from your HTML to the relevant CSS rule. First click on the name of a class in your HTML: ...

Google's John Mueller was asked if Google "looks at "CSS .Class" to comprehend the structure of a page; or a section of content that clarifies its SERP Features." John responded on Twitter saying ...

Google’s Search Relations team explains how CSS affects SEO, addressing myths about class names, pseudo elements, and page performance.