Claude Code tip: before you ship a vibe-coded site, let Opus 5.5 send 𝟱 𝘀𝘂𝗯𝗮𝗴𝗲𝗻𝘁𝘀 through 𝘁𝗵𝗲𝘀𝗲 𝟮𝟬 𝗰𝗵𝗲𝗰𝗸𝘀 and fix everything in one pass: 1. design that holds together • write a DESIGN file first and tie every color, font size, spacing and radius to it • keep the palette tight and the type hierarchy clear • same kind of button, card or input = same look • flat page? add emphasis. crowded page? cut • text stays readable on dark and light backgrounds 2. mobile • nothing scrolls sideways or spills off screen • add a real mobile menu • buttons big enough for a thumb • the layout survives enlarged text 3. every state • loading, empty and error each get a proper screen • every button gets its own hover, pressed and disabled look • form errors show up next to the field, plus submitting, success and failure messages • modals, dropdowns and tabs switch with transitions 4. click it like a real user • run sign-up and checkout from start to finish • hunt down dead button