For the past few years, I haven’t had too much trouble out of IE — only because I’ve become familiar with its quirks. I know that floats need display: inline to fix the margins, position: relative or zoom: 1 needs to be added to misbehaving elements to trigger hasLayout, and height: 1% will make boxes stretch to contain their floated children. That’ll fix IE6 90% of the time. But today, I struggled with something I hadn’t run into before: Lack of Multiple Class Support

I was trying to reference elements with multiple classes in my CSS:

.aside.login {
  properties: values;
  ...
}

All the other browsers (including IE7) work with this just fine. IE6, however, only sees one class. I wish I had known about this before I spent most of my afternoon trying to figure out why rules were getting applied to things they shouldn’t have.