Follow-up to 5d0a07bf9d.
See T48947#3641618 for a detailed explanation of the
problem this is fixing. Essentially, our CSS has to be
compatible with both new and old HTML to avoid problems
with cached pages on Wikimedia wikis. To do this, we
add a CSS class to the body and make the new CSS only
apply on pages that have this class. This patch should
be reverted when the caches expire.
Bug: T48947
Change-Id: Icf26e6690b59f470765b2634534d18d2df25ee2a
Logo used in print styles. Keys are url, width, and height (in
pixels). Note that this solution only works correctly if the image
pointed to by url is an SVG that does not specify width and height
attributes, or its width and height match the corresponding variables
below. Alternatively, a PNG or other type of image can be used, but
its dimensions also need to match the corresponding variable below.
That in turn may result in blurry images, though.