This page in Tiger Settings refers to a Height, Height on subfolders and Height on pages.
I assume it represents the “cropped” height of the theme image. However, whatever setting I put in, I do not notice a change in theme image height.
What are these settings supposed to do?
Just tested it, and it works as advertised - if the height of the hero/theme image is changed in the settings, the height is changed in the album - see screenshots. It changes the displayed height of the theme image.
Because the image is shown full width, and the width of the page will vary with the size of the monitor, the actual image cropping is handled separately (complicated subject). But even the theme image cropping mask shows the change - see screenshots.
Of course, you have to Make Album again, and you may have to refresh your browser cache when viewing the result.