Everything I vibe-coded kept coming out the same: purple gradient, three-card row, rounded-2xl everything, an italic serif hero I never asked for. The model fills any decision you leave unspecified with the average of its training data, and that average is the "AI look." So I catalogued the tells, then wrote them up as a drop-in rules file. Rename it to CLAUDE.md, .cursorrules, or AGENTS.md and your agent designs against the defaults automatically. It is phrased as "prefer a rea...