Photoshop is a much more powerful design tool than CSS, and given free reign to design at will, designers will often tweak things like font settings to a degree that cannot be recreated on the web.
Is there any way to lock down Photoshop, or perhaps run an equivalent of the Office 2010 "Compatability report" that shows the designer where they have designed something that cannot be rendered on a web page.
Something like the old-school "web-safe" colour palette, but for an overall design.
No.
While there's definitely some overlap and lots of situations where Photoshop is more powerful than CSS, the reverse is true as well — CSS can have multiple shadows and insets on the one object.
Also, depending on the browsers you wish to target, the abilities will vary, too.
I think your best option will be research and knowledge.
If you do want to go down the automated route, Fireworks CS6's new CSS properties panel may be worth a look.
Although you can design things in photoshop that can not be created in css directly you can almost do everything in that is in the photoshop file if you use slices aswell as pure css.
Somthing that might help bridge the gap between photoshop and css a little better is css hat i havnt tried it myself but looks like it could be pretty useful.
