I'm in lurrve .........
Browsing the forum and searching on "color" I discovered that there's a Chrome Extension for YNAB. Now I don't usually like extensions but I thought "what the hell?" and got it. and it solved my hatred of the two things in the web YNAB - namely, orange and the fixed width inspector in the Budget pane.
Despite not being colour-blind I activated that setting and hey presto, orange turned blue, thereby confirming my hunch that I was actually reacting to the actual colour rather than what it stood for.
The other irritation, the fixed width inspector (whoever developed the Extension/Toolkit actually gave it a name I understood) can be shrunk, thus giving more space if you need larger font size.
This find has made my choice to stay with nYNAB go from "mm, maybe..." to "almost definitely" in minutes.
My only sorrow is that it has taken a 3rd party to do it, and not YNAB.