Error messages are never a good thing to receive when you're a user; they always make you feel you've done something wrong. Case in point:
Now, forgive me for being pedantic, but the heading and message don't say the same thing. The heading is correct - 503 means the service is unavailable, it's a server error. Yet the message informs me that I or my browser has done something wrong; that's right, somehow by just navigating to the web site I've caused the server to fail. I'm savvy enough to realise that this is just because the developers were too lazy or incompetent enough to provide a better message; it's not hard to do - "Sorry, the site is down - it's our fault - come back later". Friendly, no worrying by the user.
As an aside, the header and message are also a table with two rows that are fixed width, with the table and table cells having inline styles. I hate to blame the developers again, but what choice do I have? It's possible it's some CMS system or tool generated, but that's really no excuse; the tool should produce decent markup.