Is there any equivalent to Stylish for Firefox that's available for Opera?

The only thing that prevents me from converting from Firefox is the lack of a clear Vista theme (like Glasser + default Firefox 3 Strata theme) and the lack of a stylish equivalent. Opera feels much more pleasant to browse with and do not need any tweaks or installation of unnecessary addons but I do want to customize some websites like Wikipedia with the Stylish extension in firefox.

Here's an example:

http://userstyles.org/styles/7582

Before:


After:

Opera supports user stylesheets right out of the box, just go to Tools -> Preferences -> Advanced -> Content -> Style Options, and there's a setting to choose your own custom stylesheets.

There are also some preset stylesheets in the View -> Style settings.

Read OP's post again before replying.

These are javascripts, not pure stylesheets.

Add somewhere (anywhere) on your disk a UserJS folder (name doesn't matter) and tell Opera (Tools > Preferences > Advanced > Content > Javascript Options > User Javascript Files) to use that folder, it will load all scripts inside it. To toggle it on / off use http://userjs.org/help/resources/toggle-user-javascript buttons.

This particular JS doesn't work well in Opera it seems, looks borked, also, for me it takes a half second before the JS is applied so I actually see the normal Wiki page before it gets changed:

Click to view attachment

^ Yeah, that's what happened to me too.

I abandoned Opera and went back to Firefox 3. There's no difference between the browsers except that Opera is much smaller (installation) and it has more features out of the box.
Firefox 3 has Stylish, the special address bar and other extensions that provide the same features as Opera's default features. Apart from that, browsing feels the same on both browsers. I can even emulate Opera's scrolling in Firefox and make it feel "faster".

huh? he's asking for the Opera equivalent of Stylish, not GreaseMonkey.

UserJS is the equivalent of GreaseMonkey, Custom Stylesheet is the equivalent of Stylish. Of course functionality-wise they are not strictly the same, for example it's impossible to style Opera's interface with a custom CSS or script.

For site specific styles, just apply custom stylesheet to site specific preferences.

*nvm