What they did
u/Amazing-Mirror-3076 had never liked their company website's design, which originally cost about $10k and a couple of months to build. On a Tuesday evening before going out to dinner they asked Codex to propose three or four designs, chose one, and told Codex to implement it across the site. They used plain Codex to generate HTML mockups, without Figma or other design tools. Over the following days they went back and forth with it on layout, colour details and pages it had missed, and on another night left it optimising load performance.
How it went
By the next morning Codex had updated about 112 unique pages plus the CRUD screens. Wednesday went on revisions, and at one point it reverted part of the site to the old design for no clear reason. Thursday and Friday took a couple of hours each of review. After the overnight performance pass the site scored 100 on every Lighthouse metric, which it had never done. The new site was due to deploy the next day after a final test run.
Worth knowing
Expect a few days of human review after the overnight run: the agent missed some paths and once rolled back its own work. A commenter warned that Codex-made sites can look recognisably templated.