tangor, your answer is fantabulous :)
You're right: It is
about finding that sweet spot between rolling over and just taking whatever they throw at you and coming unglued.
In reality, is this CSS thing really really really that big a deal? And secondly, if they are going cheap is there a way you can satisfy that and still make a profit? That's the bottom line. You know the value of your work, your time, your future with the client. When things go south on their end (pinching pennies) it's a sure bet that at some future time you will not be paid, even with threat of a lawsuit. Been there, done that a few times until I quit being the "nice guy with answers" and the "business man with results". I'm that way now, even with family and friends when it comes to my coding.
Find your comfort level, that's what all the above is about. Coding for dollars is a tough business, don't let anyone tell you different.
In the greater scheme of things, no, it's not a really, really, really big deal. But then again, it is. If I work on the site and have things just so, then come back the next day and things have been edited to screw things up, it's time lost. If I come back weeks or months down the line and there are lines of code I didn't put in and they're causing problems...well, I just have to remind myself that at that point, it's a new project.
I think for me there's a disrespect that gets to me. I have an emotional response to it. I'm sure I shouldn't, but I do. It's like people assume that they can do what I'm doing, that they can just go in a mess with things, no biggie. It amazes me that this happens after years of working with me, that they would disrespect or not value our relationship any more than this. But then, it gets back to money...
So yes, I do just have to find my comfort level and what I'm willing to deal with and at what price I'm willing to do it.
For anything else I'm your Huckleberry."
And DO NOT FIX THE MODIFIED CSS!
And if what they want changed involves CSS, tell 'em why. ONCE AGAIN. Repeating, over and over, "It ain't broke, quit trying to FIX it! Take more photos! Write more Content! Leave the CSS alone! Oh, if I have to work with CSS YOU HAVE MODIFIED, there's 100% surcharge. IN ADVANCE! I'm not kidding!"
Then walk away.
You know you want to do that, but that's pretty extreme. :)
Yes, I would love to do that sometimes, and yes, of course it's extreme. But you know why
I would love to do it? Because after seven times of being assertive and kind and them acting as if you've said nothing, or making excuses for why they mess with code, you get frustrated. It's like you're talking to a wall.