Changing orientation on mobile ads
In some cases you may wish to have a mobile ad respond to orientation changes, with separate landscape and portrait layouts. Google Web Designer lets you handle this two ways, using either responsive layout or alternate pages.
1. Responsive layout
2. Alternate pages
You can create alternate orientation pages for each page by going to the Page properties section of the Properties panel, and setting the Alternate Page to the page ID of the page with the opposite orientation.