Function column_classes 

pub fn column_classes(column: &Column<'_>, opts: &Emit) -> String

Every class a cell of this column carries.

The column’s own name, how wide it asks to be, and when it drops. A header cell has to carry the same three or the header and the body disagree about which column just disappeared, and a renderer emitting its own header row should call this rather than assemble the list a second time.