This is the orientation video: what the Solo settings page is made of, why some sections are missing, and what happens the moment you press Save.
Finding it, and reading its shape
It is core's own theme settings route — /admin/appearance/settings/solo, reached from Appearance by clicking Settings next to Solo. What Solo adds is a stack of collapsed sections above Drupal's usual logo and favicon controls, each opening into vertical tabs. In order, you get the Theme Blueprint, Global Site Settings, Libraries & Fonts, Search Results, Predefined Color Schemes, Page Wrapper, then one section per active region, and finally Social Media Links and Copyright & Credit.
The Blueprint section at the top is a map rather than a form: it draws every region in position and explains what each is for. It is the fastest way to learn the region names before you place a block.
Why a section you expected is not there
Solo classifies regions three ways and tells you so in a message at the top of the page. A region is Enabled when it holds at least one active block, Disabled when it holds only inactive blocks, and Empty when it holds none. Empty regions are not rendered on the settings page at all, and the message also counts how many regions are enabled in each of the four containers. So if the Footer settings are missing, the answer is at /admin/structure/block, not in the theme.
What Save actually does
- Writes the values into the theme's configuration object.
- Rewrites the dynamic CSS and JavaScript files, or deletes them if you emptied those fields.
- Resets the asset query string so browsers do not keep an old copy.
- Clears the theme registry, library discovery and Twig caches, and invalidates the configuration cache tag.
In other words, no manual cache rebuild — if a change has not appeared, suspect a reverse proxy or a browser cache before you suspect the form. Keeping a record of what you changed is still wise; this piece on protecting your Solo settings covers exporting them.
Sub-themes built on Solo get the identical form. Solo supports Drupal ^10.1 || ^11 || ^12 with PHP ^8.1 — theme page.
If you would rather have this set up for you, Drupal theming services covers the work, and recent projects show the result.
