What matters
Google Display Ad — 970×90 Large Leaderboard dimensions at a glance
The 970×90 Large Leaderboard spans wide desktop layouts. It offers more horizontal space than the standard 728×90 but is only shown on wider screen placements.
On wide-screen sites, this format dominates the top of the page more completely than the standard leaderboard, commanding more attention.
Designing as if it were a 728×90 wastes the extra width. But the 90px height constraint remains — don't try to add more vertical detail.