You're doing A with framework B and that landed you in court.

I advise you to use C, possibly couple it with D so you can fix the problem you have.

If they don't want to listen, let them find another consultant. Save your nerves and keep choosing who you want to work with. Not every client is worth every dollar.

Hmm I don't clearly understand where WCAG actually breaks with bootstrap. It's just a responsive layout framework with a class composition approach and some basic functionality.

It should have nothing to do with it, i don't like it that much either but I found out that a big portion of the people just don't know enough to actually build a responsive homepage.

That's it about the technology. I think your reasoning is not conclusive but taste. Bootstrap and WCAG are not mutually exclusive. But stupid applications of any approach can lead to failed results.

To your concrete problem, I agree with Milica she puts it very reasonable.

You are the expert you were hired to give them advice, if they want to push another agenda, you either don't have enough evidence or they are ignorant.

I would rather push on the principles of how WCAG works and not against a specific technology, but if you really can't stand it -> her approach seams to be the most professional to me.

I've definitely been in the presence of absolute geniuses who knew my area of expertise way better than me before ;) I can relate to that feeling. I don't have any one particular person or situation in mind, but I'll share my answer:

Q: How do you deal with clients who think they know more than they do?

One answer: Never let them know you think they are wrong, but try to find a way to educate them, or learn (more like re-learn) the lessons you already know in a way that they can also witness and experience.

I see this one all the time in graphic design circles, where designers sit around telling stories about the dumbest, most demanding clients and laugh at how little they knew about stuff, but to me that's a failure in communication. There's a gap there, and I think at least 50% of the responsibility for bridging that gap is from you, the actual trusted expert.

Ever since I realized that in my own client relationships I haven't had any of those 'nightmare clients', and I don't think it's because they went away, I think over time you (can) learn how to bring them up to speed, and share your understanding with them to help them see the same things from your perspective. But that's not instantaneous, and it isn't always effortless. Sometimes it's easy to explain something (like here's why 'above the fold' is a concept that doesn't apply to web design) and sometimes you almost have to establish a base vocabulary for the concepts you're talking about and teach them how to think and speak about something before you can explain what you know about it.

In the end, I believe most 'nightmare clients' can become slightly smarter, slightly better, and hopefully learn to trust your judgement more. The more you teach them and guide them, the more they will listen to what you have to say when it's time to give personal opinions on things.

I agree with Milica who put it very succintly. Even as a consultant, a culture fit is very important. Most people assume that this is reserved for employees only. As a consultant, if you've been brought on board as an "expert" in a field, then they would do well to take your advice. Disagreements are normal, but if you're this unhappy about it, walk away. No shame.

Having said that, there are times in the past where I've disagreed with the client but still went ahead and did what they asked for. In those scenarios, it's about covering your own ass first. I'd make my disagreement with their final decision in a written format to ensure a paper trail to the saga. At the end of the day, it's their product, their company and their team. It's up to them how to run the show. I was there to help in any way I could. If all they wanted was a pair of hands, that's all they get. If the client actually wants a brain to go with it, I'd be happy to oblige, but I'm not killing myself over it. Obviously I never renewed their contract.