I don't understand your reasoning.

In my opinion, classnames should say what the HTML element represents, and a stylesheet contains the definitions for styling and sizing.

Your HTML should not include information about the size of an element. Your HTML document should represent the content & structure of your document. Your stylesheet is then responsible for layout, design, color and dimensions.

It is all about semantics. See: https://maintainablecss.com/chapters/semantics/

By writing the column sizes in the HTML, you're effectively reinventing inline styles