Issue #2321505 by LewisNyman: Split Seven's style.css into SMACSS categories.
Issue #1885564 by Cottser, SebCorbin, joelpittet, drupalninja99, jenlampton, longwave, aboros, trevorkjorlien, socketwench, shanethehat, mbrett5062, rteijeiro: Convert theme_task_list to Twig template.