Use 'normalize' module from 'mediawiki.skinning'
Also remove home-baked 'normalise.css'. Even though we're not (yet)
covering all rules – some are not used in MW context like canvas,
some are covered by 'elements.less' like mark, some will probably
be added with 'normalize' now part of core like more form specific
ones – it's not a the best way to have such unmaintained, and in parts
unspecific fork living as base code for new skins.