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 “not that I’m aware of.”

The .class selector selects elements with a specific class attribute. To select elements with a specific class, write a period (.) character, followed by the name of the class. You can also specify that only specific HTML elements should be affected by a class. To do this, start with the element name, then write the period (.) character, followed by the name of the class.

So no, Google does not use the CSS .class selector for this purpose. Google does render your page, knows the layout based on the rendering and make visually understand the structure of the page that way but not by simply looking at your CSS.

Here are those tweets:

Not that I’m aware of.

— 🦙 johnmu.xml (personal) 🦙 (@JohnMu) April 17, 2022

Forum discussion at Twitter.