Wow! Didn't expect that fast reaction!
Looks good, only one issue I have is some font shifting (see attached screenshot). It happens due to bigger font that I use on my laptop.
Just a few more proposal, please don't consider it as any kind of criticism!

. This is just my ideas, nothing more.
1. Would be good if the last chosen value was stored. i.e. If I choose 30 minutes, would be good to have it already selected after next start.
2. How about a popup window 30 seconds before the shutdown with "Cancel" button on it? Sort of reminder.
3. When this timer tried to shutdown my computer one opened app didn't let it. I found my notebook working in the morning and still waiting for a confirmation for forced shutdown. mb some check box for a forced shutdown?
eye-candy part
3. mb rounded edges? Like default weather gadget
3. I'd remove the legend "Action" - it is pretty obvious, and make this field same size as duration field.
4. I'd make the timer a bit bigger, or reduce the size of the window. There are too much free space around.
5. Lists (duration and action) and the header look a bit off-centered
Also donated a beer to you