I discovered this today when my overflow content appeared cut-off in Firefox and IE. It appears this was reported to Mozilla and closed as invalid in Bug 748518 – padding-bottom/right(block-end/inline-end) is ignored with overflow:auto/scroll because it extends in from the border-box rather than out from the scrollable area and someone there suggested bringing it up with the CSS team. I did a search for padding-bottom overflow on the www-style list and didn’t see anything.

Previous practical discussions on Stack Overflow include Bottom padding not working on overflow element in non-chrome browsers and padding-bottom is ignored in Firefox and IE on overflowing elements with no content.

Perhaps this is already clear and Chrome has it wrong? I’ll admit I’m not enough of an expert on the spec to be sure, just hoping for consistency.