I'm not joking: much of the light gray text on your site and your screenshot becomes literally unreadable when my LCD monitor is viewed at certain angles, not far off perpendicular; it becomes the same color as the background. My monitor may not be expensive, but it's not a cheapo, no-name one either.
I absolutely detest this current fad of thin, light gray text on white backgrounds. Instead of using high-contrast, easy-to-read text, people are using gray-on-white, white-on-gray, even gray-on-gray, and always with thin, narrow-stroke fonts and enormous amounts of whitespace.
And if it's hard to read indoors with no glare on a full-size screen, imagine trying to read it on a mobile device, outdoors, with sun/sky glare, or indoors on a reflective, glossy screen with fluorescent lights' glare.
I mean, look at the bottom of your page. One of the most important links on the page, the "Contact" link, is very light gray, thin text on white. When the cursor hovers over the bottom of the page, the links become slightly darker gray. And when the cursor hovers over a link, it becomes an even darker--wait for it--gray. You've effectively made the "Contact Us" link invisible.
And the screenshot of your product exhibits the same problems: the UI fades into the background to such a degree that it is difficult to see. This is bad enough when talking about a web page whose primary purpose is to look stylish, but your product's primary purpose is to be a usable tool. Are you trying to make the wiki equivalent of Das Keyboard?
Where do these fads come from?
For a good illustration of the problem, I just discovered this web site (which also lists HN as an example of the problem): http://contrastrebellion.com/