Set the font size you want on the narrowest and the widest screen. The CSS clamp() line scales smoothly between them and never goes smaller or larger. Drag the slider to preview any screen width.
The quick brown fox jumps over the lazy dog.
How it works
clamp(minimum, preferred, maximum) keeps the size between the two limits. The preferred value mixes rem (so it still respects the visitor's own font size setting) with vw (a share of the screen width), so text grows in a straight line from the narrowest to the widest screen.