WordPress Default 1.5 theme problem in Opera 9

.navigation <div> contains only floated elements (.alignleft, .alignright) which aren’t part of document flow. Because of that Opera 9 collapses margins of <h2> with .navigation and renders <h2> text between next and previous links.

I’m not quite sure if that is Opera’s bug or some quirk in CSS specification, but there is easy way to fix this issue. Add rule:

.navigation {overflow:hidden}

Overflow will not actually hide any content, because .navigation has height:auto, but the side effect of overflow is that it will make this wrap around it’s floated children and push <h2> down where it should be.

This is bulletproof method suggested by PPK:
https://www.quirksmode.org/css/clearing.html