Via thinkvitamin and  tipster: a couple of notes that may resolve a couple of outstanding issues I’ve had with PNG24 transparency use…

Set width and height for the element/s containing the transparent background image […] (also, bear in mind that the background images can no longer be tiled or positioned via ‘background-position’)

Apply  position: relative; to any contained links to ensure functionality

The first point means I’ll probably not bother trying to tile a drop-shadow background image to a variable length column again. Time to switch to progressive enhancement with Photoshop CS4/Fireworks/other tools’ ability to stuff alpha transparency into  regular PNG8 files.

The second point is probably the better answer to my last PNG problem post.

Main post about how to work with PNG24 alpha transparency and IE6