Justin Tadlock 2 years ago The Post Styles feature was removed from Hybrid Core last year simply due to low usage amongst theme authors (it was built primarily as a developer feature). Stargazer was updated to use that version of Hybrid Core earlier this year. There just wasn’t enough interest in the feature to keep it. Given the multiple plugins (like the one you’re using) and low usage numbers, it didn’t make a lot to sense to maintain the feature. With all the above said, I’d be happy to see about pulling the old code out if you absolutely want it. Or, perhaps, look into some other solutions. If you just have a page or two, it’d be pretty simple to apply a custom stylesheet to it with a few lines of code (not quite as nice-looking as a meta box, but it’ll get the job done). Whichever path sounds best to you is good with me. Side note: Another thing you might look into is the Gutenberg plugin. If you haven’t heard of it, it’s going to be the new editor for WordPress 5.0 and is currently being developed. https://wordpress.org/plugins/gutenberg/ Pretty much everything I (and most other theme authors) are going to be doing will be centered on that, particularly for per-page designs.