line-height

line-height is tied to font-size, which is rooted in browser font-sizing and environmental resolution, while line length is based on width, which is rooted in viewport dimensions

line-height is used to control leading, the amount of white space between lines of text. Leading should increase with the length of measure.

Opera Mini Support

Opera Mini does not support line-height:

Mini does not support the line-height css property at present, since testing showed that it generally meant less text fitted on any individual page, requiring more scrolling from the user.

Opera Mini: Web Content Authoring Guidelines