I suppose this explains why I've never really liked CSS or the design-heavy web: I was never willing to give up that control over my machine. I still resent the way modern "user-agents" aka browsers give every jackass designer out there more control over what my machine is doing than they retain for me.
I feel your pain due to a different reason. After seeing how the major Linux UI toolkits support consistent theming of all the programs using them, original styles/themes be damned, the lack of a consistently-applied theming system/mechanism among web applications is all the more obvious. With web pages this generally isn't an issue (barring annoying/just crap ones) but with web applications, why should their visual appearance and design be arbitarily (from my perspective anyway) decided by a developer/designer with no effective way to alter/change/override this either cleanly or consistently over multiple applications.