I manage a set of websites with a largely non-technical user base. We want to occasionally provide site-wide notices for forthcoming planned maintenance.
We've tried using a messages with red backgrounds but they are too similar to error messages, Github style green messages but they're not noticeable enough. The color schemes the sites use for error messages are similar to the jQuery UI green, red, beige-yellow.
Is there a good compromise for making these site messages immediately noticeable, but not too intrusive?