Type does most of the work
If you change one thing about how a site looks, change the typography. A clear scale — sizes that step distinctly, weights used to signal hierarchy, line height generous enough to read comfortably — accounts for more of the impression of quality than colour does.
Most dated sites have a compressed scale where a heading is only slightly larger than body text and everything sits too tight. Regenerating the page fixes that as a system rather than as a series of one-off adjustments.