So, I've been messing around with HTML and the like in the Byond Browser, and I've come to the understanding that it uses IE.

However, I have no clue -which- version of IE it uses, which makes it difficult to determine what I can and cannot do with my CSS.

Anyone care to fill me in on the specifics regarding what BYOND uses?
Depends on what operating system you're on. If I recall, Windows XP users had a modified version of Internet Explorer 5, and Vista onwards uses Internet Explorer 7.
Ah, so the version is dependent on the user's OS? In that case it's fair to plan for IE5, as users still use XP (Including myself).

Man that sucks... IE5 is horrible... I wish it used Chrome. If you actually update your IE on XP, will it use the updated version? Or is it a modified browser that comes with the byond installation?
It uses whatever version of IE you happen to have installed, I believe.
In response to Deathguard
src << browse("<script>document.write(navigator.userAgent)</script>")

Says IE7 on my windows 7 system (which has IE9).
I stand corrected, LordAndrew is indeed right.
Should be IE6 at the earliest, actually.
Ah, alright then. If it's IE6, that's a little better. Thanks for the responses.
You should plan for people using IE8 or IE9. IE6/IE7 are too old and should be safe to ignore -- if people complain, tell them to upgrade.

Ideally everyone would be running IE9 as it's much better than IE8 (which is much slower at rendering and processing Javascript code).

I very much look forward to the day that the browser control has an optional "use Webkit" checkbox that can be used to use Webkit to render pages and process Javascript (if I'm wrong and Webkit does not include a Javascript engine then something like Google Chrome's V8 should be used IMO).
You should plan for people using IE6. JBoer is too old and should be safe to ignore -- if people complain, tell them they can't upgrade.

Read the topic. You can't just go and easily update the IE frame that BYOND uses, nor should you expect people to.

Little tidbit - you can set your web control to use IE9 by creating a dword with the hex value '270f' named dreamseeker.exe in HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_BROWSER_EMULATION
Good luck requiring your users to do this. :)
In response to Murrawhip
Give them a .reg file that does it automatically. (All they have to do is open the file and authorize the change.)

Contents of the force IE9 file:
Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_BROWSER_EMULATION]

And another file that undoes the effects of the previous file:
Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_BROWSER_EMULATION]

And I put these into a zip file for easy access and use.

But, even so, you can't really require all of your users to do this. Maybe BYOND can do this automatically in their installation process.
I have a feeling that the IE browser component is just too ingrained in Windows that BYOND can't have complete control over it. If BYOND used a Webkit-based control of their choosing they'd have more control so that Dream Seeker would consistently use the same browser on all computers.
Complex Robot: Thanks, I wont go through all that trouble though, it seems a little bit too.. iffy. My main ideas were for HTML/CSS, I don't extensively use JS in the byond browser (although I -would- like to, but a lot of properties and methods as it says, simply aren't supported by the browser)

Webkit would be an awesome upgrade. Too bad it doesn't come standard on all OS', Byond would have to include it in their installation for it to become the browser.