The color should be determined by the rest of the site. Only some colors fit with other colors.
You notice how there are almost no orange, purple, or brown websites? Its not just because of what looks good;
Its because they rely on compound colors. Compound colors require more than one rgb component to achieve; therefore, websites in those colors won't look the same from monitor to monitor because all monitors are different.
In this forum, the background is a bright blue, which, while a compound color itself, its not dependant upon that. If you turned all the red out of your monitor, you'd still be able to use this site.
Take all the red out of your monitor while looking at a deep purple site, and you will not be able to use it.
Perhpaps this is why so many websites center around white, black or grey. Since monitors usually have brightness/contrast accessible, people can easily adjust for that (like trying to look at my superdark site). A laptop can be brightened by taking it into a dark room.
But when the colors are off, the average person doesn't know how to correct them. So most web designers simply stay away from 'iffy' colors. Brown is by far the worst of all of these, as its a combination of all three colors.
As a side note, those pill shaped buttons look really good; I don't know what backdrop they will end up against but they look nice as they are.
As another side note, your comze site has an oxblood link color against green text; what this says is 'here's a link, but i'm not that thrilled with it." I've made more than a few websites, and i can tell you, that if you don't present your links like they're awesome, we'll assume they aren't. Links ideally should pop against text, whether by being brighter (i. e. yellow links against green text) or by being more saturated (the standard blue links against black text). Just a suggestion.
