Device supports 3 fonts:
When the font is set to medium, h5 and h6 must use small and large for h1, h2,
and h3 must use large. When the font is set to small, h4, h5, and h6 must use
small and h1 and h2 must use large. When the font is set to large h6 must use
small and h1, h2, h3, and h4 must use large.
Otherwise all headers should go from large h1 to small h6 with each one different.