Please, make the link to the examples more visible. If it hasn't been on HN, I wouldn't have taken the time to look for them (never saw the topbar) : I clearly don't want to download them if I cannot see them first. Also the gigantic banner on the frontpage is useless to me, I didn't read it, at all.
Other than that, I find the website, including the buttons, quite clean.
noted, trying to get more feedback on that jumbo banner. i'll see if maybe a link to "getting started" on the bottom could lessen people getting "lost" as well.
The way I see it : no banner, a huge "CSS3 Microsoft Modern Buttons", some examples, then a huge "See more" button (like your "Download ...") and a less visible "Download" button (or maybe at the top of each page, something like the GitHub's "Fork me"). All before the fold. Just my 2 cents though ;)
Other than that, I find the website, including the buttons, quite clean.