In typography, measure is the width of a line of text, in characters. Choosing a reasonable measure is critical for the comfortable scanning of successive lines. The Elements Of Typographic Style considers any value from 45 to 75 to be reasonable.

:root {
  --measure: 60ch;
}

* {
  max-inline-size: var(--measure);
}

html,
body,
div,
header,
nav,
main,
footer {
  max-inline-size: none;
}