Update body line-height to unitless value

This issue is visible in all branches, it is easily fixed though

fusion-typography.css sets line-height 150% for body

It should set line-height: 1.5

While this appears trivial, it makes a big difference: with a numeric value (e.g. 1.5), it is multiplied by the height of the element where it is being applied.

With a percentage, it is converted into pixels (e.g. based on the default size for characters in the body element) and that same pixel value is then used elsewhere.

When a heading spans more than one line, especially a h1 heading, the characters in subsequent lines are too close to the characters above them.