Css: Unitless "line-height" value is used incorrectly

According to the CSS specs for "line-height" by the W3C, a unit-less line-height value (number without unit) should be used as follows:

The used value of the property is this number multiplied by the element's font size. Negative values are illegal.

Browsers do this correctly, but Qt does not. Qt seems to interpret the line-height value as pixel value.

See attached screenshot and example.