Converting px to rem in Tailwind, Bootstrap, and Vanilla CSS

How conversion works in each ecosystem—and where the gotchas live.

Vanilla CSS

rem = px ÷ base. With the default 16px base, 24px = 1.5rem.

Tailwind's spacing scale is already in rem. p-4 = 1rem = 16px by default.

Bootstrap 5 uses rem-based spacing and type. Override $font-size-base if needed.