According to https://www.salesforce.com/content/dam/web/en_us/www/documents/platform/salesforce-only-in-lightning-features.pdf:
Use new Lightning App Builder attributes to display the highlights panel in less space, show fewer buttons, and change the orientation from horizontal to vertical.
However, I see no such option. The problem is when I place the Highlights panel in a region on a template which I have myself defined, even one that extends across the entire width of the page, it still displays it in vertical mode.
How can I force the Highlights panel to display in horizontal mode in a region I've defined in my own template, whether or not it crosses the entire page? Are there any know reasons why a region in a user-defined template would cause a Highlights panel (also the Path component, by the way) to display in vertical rather than horizontal mode?