The Site Reverted to a Blank Word Document: Here's How the Actual Bug Got Found

I opened AI with AI Labs and every page looked like a blank Word document. Default blue links. White background. No cards, no shadows, none of the design that was supposed to be there. It looked like the CSS had never loaded at all.

The instinct in that moment is to start guessing. Reinstall something. Clear a cache. Push a change and see if it fixes itself. I didn't do that. Instead, I had Claude Code walk through actual diagnosis, one specific check at a time, before touching anything.

It turned out to be a mix of all three. Not one clean root cause. Three separate small breaks, stacking quietly across nine different pages, each one contributing part of the reason the whole site had reverted to looking unstyled.

The diagnostic checklist

Here's the part I want to be specific about, because it's the actual lesson: name the real root cause before you touch anything, even when the fix looks obvious from the screenshot. A screenshot of a broken site tempts you into a fast, confident guess. The guess is usually wrong, or at best it's only fixing one of several overlapping problems, which means the site looks fixed for a moment and then breaks again somewhere else.

While I was already inside the actual styling system fixing the three-part break, I made a bigger call than just restoring what was there before. The dark-only theme wasn't working well anymore as the site had grown. So instead of just patching it back to how it looked, I built a real light and dark toggle. Brighter as the default now, with the dark palette kept around as the night option instead of thrown out entirely. Rebuilt the homepage hero while I was in there too, since it needed the same attention.

An emergency fix turned into an actual design decision, because I'd already done the work of understanding exactly what was broken and why, instead of papering over it.

If you hit a styling bug that looks total and sudden, especially one that looks obvious from a screenshot, walk through it in order instead of guessing. Named root causes fix cleanly. Guesses usually just move the bug somewhere you'll find it later.