Gin dark mode (html.gin--dark-mode) is on by default and the previous CSS relied on Gin custom properties that didn't resolve here, causing black-on-black/white-on-white text. Now uses self-contained explicit colors with a dark-mode override block. Error rows get a thin red border instead of a background fill, as requested. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>