Nice advice notfred 🙂 , though you do have to consider that there's a fine line between web developers and web designer's. Design is design, Development is development so you can't expect most real designers to deal with the underlying code.
I agree though, that a lot of "web designers" advertise themselves as such, but isn't necessarily so.
Additionally, the way most designers and developers work - especially freelancers like me - having to fix and perfect a project to work in every possible monitor/color depth/platform/browser is next to impossible. Add that number of combinations to the number of projects to be made in a single month and it just gets even more complex. Thus, there has to be a compromise somewhere. My first order of approach is usually to look at the logs of existing customer sites and see which is the #1 and #2 platform/browser used and base the site coding and design on those. There's never any real guarantees that what works today will work tomorrow given the "upgrades" that software developers makes to their packages.
Then of course there's the usual corporate mumbo-jumbo, "I don't care if it works on Netscape, as long as it works in IE and it looks good!". :disgust:
To add to notfred's discussion, if you are into real design... even the colors itself will differ from one PC to another - even given the same exact OS, browser and monitor. Just gets more complicated eh? 😉