Currently the h4, h5, and h6 headers are all styled with the same size and weight and subsequent apparent importance, despite being used on the page to designate a hierarchy of sections. As a result, h4-h6 sections can appear as though they belong to the wrong parent section, confusing readers.
Example:
http://wikimediafoundation.org/wiki/Staff_and_contractors?showall=1
'Product Management' is a subset of 'Product', but due to the skin formatting there is no way to tell when using Vector.
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**Previous Patches**:
* <https://gerrit.wikimedia.org/r/164712> (mediawiki/skins/Vector) Adjust header sizes to scale apparent size according to header weight"
* <https://gerrit.wikimedia.org/r/162304> (mediawiki/skins/Vector) Make h1-6 sizes consistently different"