I want to expand on something that Journeyman Geek said in this answer. (I'm the user he referred to.)
I have some vision problems (root cause, aphakia) that affect acuity (thus bigger fonts and fixed focal distance), light sensitivity, and (some) color perception. I'm used to having to make browser-side adjustments when using the web (not just SE). Sometimes sites make design choices that impede or prevent those adjustments, and that's very frustrating.
For the most part, SE works ok for me with scripting and CSS-override assists. But sometimes SE design decisions play badly with my vision problems. When that happens I'm usually able to get help, and fairly often other people benefit too. For example, a userscript that ArtOfCode wrote for me to solve an accessibility problem in the moderator tools is also used by other moderators.
Users helping users is a key feature of Stack Exchange, but sometimes you really need help from somebody at SE specifically. When the new top bar first rolled out, it was very hard for me to use because of my vision problems. First I vented my frustration (elsewhere); when I calmed down I wrote this detailed description of the problem, with specific requests. I made sure to describe the problem rather than just saying "please do X", and to be clear about needs versus wants. And -- this is important -- even though I was upset, I wrote a calm, descriptive, detailed post, not a rant.
I was contacted by the product manager working on the top bar. We had a meeting during which I shared my screen and showed him the kinds of adjustments I make already and how the new design was causing me problems. It was a really helpful and productive meeting, and they updated the top bar to address both the problems I brought up in that post and some other things I pointed out along the way. The team was really responsive there. (I blogged about the experience, in case you want to know more.)
SE doesn't get everything right, accessibility-wise. Nobody does; it's a hard problem and everybody's still learning. So, as Journeyman Geek said in his answer, when you run into something you can't fix yourself, ask for help here on Meta. Sometimes you'll make a support request ("how do I do X when I need font zoom?"), sometimes you might start a discussion, and sometimes you'll make a feature-request. Lay out the problem, describe your constraints, offer any suggestions you have about how to address the problem, and be professional and polite. I've gotten a lot of help from the SE community when I've done this.
When I made that post I expected it to get a few sympathy votes, a few drive-by downvotes, and not much attention otherwise. It's currently my top-scoring answer on Meta.SE. I'm guessing that most of those voters don't share my problems, but they supported my feature request anyway.