It might seem harsh and I would not go so far as to say crazy, but you have too much invested in the colors and shapes stuff. I know you hate them, probably as

It might seem harsh and I would not go so far as to say crazy, but you have too much invested in the colors and shapes stuff. I know you hate them, probably as much as I hated working for an ad tech company, maybe more, but design is not your forte and if the remaining stakeholders trust the design you need to accept that, You have done your diligence and voiced your concerns and if you can't accept their decision you should step away while retaining as much of your equity as possible. From an alternate perspective, what would your response be if the head of HR told you that you can't use python because they hate snakes? I'm assuming you would reject that (as would I) even if the head of HR had a 10% stake. It is not a decision they have been hired to make. Just like apparently colors and shapes are not the decisions you were hired to make. How would I react? I would tell them their pea soup greens, browns and their "organic splotches" remind me of explosive diarrhea and I'm probably not the only one. Then I would get to coding the best damn SAAS I could. When user stories/feedback comes in that vindicate me I will sit with a smug look on my face in the senior staff meetings knowing everyone remembers I was right :-P