Idea Summary
Static ID property to column headers and column groups would allow us to style the headers. The metadata ID generated by APEX is not useful as it can be different in various environments.

Use Case
Header formatting is desired for consistency for situations like thick separators to divide sections of columns but does not render the same thick borders for headers, freezing columns that render a thick separator at freeze point between columns but does not render the headers with a thick border, etc.

Preferred Solution (Optional)
Static ID to headers and column groups would allow us to render a #selector to style headers and column groups.