Returns the Tailwind text-transform class for the main navigation, driven by
the global typography.nav.case setting.
Returns undefined for the 'normal' (and unset) case so each theme's own
default nav styling is preserved, letting an explicit 'upper'/'lower' setting
override it via twMerge.
Returns the Tailwind text-transform class for the main navigation, driven by the global
typography.nav.casesetting.Returns
undefinedfor the 'normal' (and unset) case so each theme's own default nav styling is preserved, letting an explicit 'upper'/'lower' setting override it viatwMerge.