Reading width is a design decision

A wide text column looks calm in a mockup. Then someone reads a whole article in it, loses their place at the end of every line and leaves halfway through.

Count characters, not pixels

The useful unit is the number of characters per line. Typographers usually point to a range between about 45 and 90, and many settle near 65 for continuous reading.

On this blog the body text sits in a narrow column capped at 65 characters. Headlines can be as wide as they like; paragraphs cannot.

.prose {
  max-width: 65ch;
  font-size: 1rem;
  line-height: 1.6;
  hyphens: auto; /* needs the right lang attribute */
}

Line height follows the measure

Longer lines need more space between them, so the eye can find the start of the next one. With a 65-character column, a line height around 1.5 feels right; headlines can be much tighter.

• Set the measure in ch, so it scales with the font.
• Keep images and code inside the text column.
• Check the French version too: it runs longer, and hyphenation depends on lang.

Readers should never notice the measure. They should only notice that they finished the article.