Yep, Steam is down (update: we're so back)
It's not just you: Steam is down right now. If this were a Tuesday around this time that'd be no big deal (Valve does maintenance every week), but on a Thursday, it's a cause for greater concern.
The store will sometimes load, but it's running very slowly if at all right now. According to SteamDB, over half a million people have checked in to see if the service is down, and I bet a good chunk of them are Counter-Strike 2 players wondering why their ranked match just imploded.
Even if you are able to login, games which require you to be constantly signed into Steam—live service stuff like Destiny 2, for example—are currently inaccessible.
We've reached out to Valve for word on the outage and will update if we get a response.