Tool
Tune a readable measure before you ship it.
Measure Lab helps you explore line length in context instead of guessing a max-width in the dark.
Most teams do not choose a reading width. They inherit one. It comes from an old container token, a copied blog template, a framework default, or a max-width value that survived three redesigns without being questioned.
The result is usually acceptable in the weakest possible sense: nothing is obviously broken, but the page never becomes easy to read.
Column width matters because text is not a decorative fill. It is a sequence the eye has to travel, line after line, with enough continuity to preserve meaning and enough friction reduction to keep attention on the content instead of the layout.
.prose {
max-width: 66ch;
font-size: 1.125rem;
line-height: 1.65;
}