Why does Firefox treat Helvetica differently from Chrome?

Question

The vertical position of text rendered in Helvetica and the size of its content area differ between Firefox and Chrome for Mac. For example, in Chrome, the descenders are clippe

Answer 1

• 'Line height is auto' => the browser gets to choose.
• 'Line height = font size' => user error: the text will be illegible, and again it is reasonable, indeed essential, for the browser to make some adjustment.

You must use some leading. Books for example may be set 10pt on 12pt line spacing.