Most WordPress themes are built to ship. This one was built to teach.
I developed TopCat Lite as the companion to my Packt Publishing book, "WordPress Responsive Theme Design Essentials." Writing a book about responsive WordPress theme development meant I couldn't ship a theme full of shortcuts. Every template file had to demonstrate a clear principle. Every architectural decision had to be defensible on paper - because I was literally writing the argument in the book alongside it.
Getting it to WordPress.org was harder than I expected.
WordPress.org theme review is run by volunteers who know the standards cold. They send it back when something's wrong. TopCat Lite went through 14 review cycles. Fourteen. Each cycle came back with specifics: an unescaped output here, a missing sanitisation call there, a template hierarchy violation. I fixed every item and resubmitted. The result is a codebase that's been reviewed more rigorously than most commercial themes built under client budget pressure.
That matters. Most people who call themselves enterprise WordPress developers worked on one big project and put the logo on their site. I've co-organised WordCamp Toronto - I was lead organiser in 2016 - and I've been the lead developer on WordPress systems running inside Rogers, the Ministry of Education Ontario, and Munich Re. I've seen what happens when shortcuts get deployed at scale. I didn't want that pattern in my teaching code.
What does "14 review cycles" actually mean for the codebase? Every output is escaped. Every user input is sanitised. The template hierarchy is clean and follows WordPress conventions. Functions.php is organised by feature area - you can find what you're looking for without reading 400 lines first. Build a child theme, override specific templates, extend it for a client project. The structure supports it without fighting you.
The responsive layout uses a fluid grid across mobile, tablet, and desktop. Navigation collapses at small widths. Widget areas stack in logical reading order on mobile - not a compressed desktop layout that happens to fit a phone screen. Typography scales proportionally across breakpoints.
It's free on WordPress.org. I've maintained it through 14 releases. If you need a custom theme built to the same standards for a specific project, that's exactly what I do.