None of the three sites has a tailwind.config.js, all Tailwind 4, all CSS-first via @theme. Widths below are the real max-w-* values in production, drawn to scale.
max-w-* onlymax-w-* only.container-wideAll three converge on 768px for article/reading width almost exactly, real, load-bearing agreement across three independently-built sites, treat it as the settled answer. The one structural gap: PeptideClear names its outer container; MarketInvoice and FundBiz never do, which is why their hub/table sections have drifted to three slightly different ad hoc widths (1024/1152) instead of one clean, named 1280.