Originally published on hexisteme notes.
Every test passed. The page was in pieces.
I was rebuilding a small internal dashboard — FastAPI, Jinja2 templates, hand-written CSS, no build step — and the layout had come apart. Timeline rows unstacked into a vertical column. Status dots floated free of their rows. Log group labels overlapped. It looked exactly like a page whose stylesheet had failed to load.
The stylesheet had loaded. All 481 tests in the suite were green. And when I grepped the CSS file for the rules that were obviously not being applied, they were sitting right there on disk, correctly written.
The cause was a comment closer. Somewhere in the middle of the file, a /* had been closed with #} — Jinja's comment terminator — instead of */. Muscle memory, from switching back and forth between .html templates and .css. CSS then did precisely what the specification tells it to do: it kept reading. The comment ran on and swallowed the next 15 lines of rules — the timeline-row grid, the feed, the bucket layout, the dot alignment — until it hit the next real */, seventeen lines down.
