Yes, the phrase "every day" acts as a noun that means "with daily frequency" (e.g., "I wear clothes almost every day"), while "everyday" is an adjective that means "common or ordinary or routine" (e.g., "These shoes aren't fancy, so they're good for everyday wear"). I agree that they are two different things, and I have been known to complain about this very issue. However, in recent years, the one-word "everyday" used as a substitute for "every day" appears to be falling into common usage as a noun (see Sia's album, "Everyday Is Christmas"). The language changes according to usage. You don't have to like it, and you don't have to adopt it for yourself. But you also don't have to get pedantic with everyperson who has adopted the new usage. Getting shirty everytime people meld words that have no reason to be melded just makes you look petty. Pick your battles. Save your energy for more important issues.

Maybe they're high. Also, maybe you shouldn't be browsing dumb shit online while working.