Tailwind 4 is amazing. Thank you! One issue I've found:

contentSize and wideSize settings from theme.json do not seem to be populating the values into --breakpoint-lg: var(--wp--style--global--content-size); and --breakpoint-xl: var(--wp--style--global--wide-size); in theme.css.

If I over ride them, everything works, i.e.:
/* --breakpoint-lg: var(--wp--style--global--content-size); */ --breakpoint-lg: 960px; /* --breakpoint-xl: var(--wp--style--global--wide-size); */ --breakpoint-xl: 1280px;