Does IE8 have rendering bugs like 6 or 7? If I make my site render correctly in Firefox 3.5, will it look the same in IE8 or will additional changes / hack / etc... be needed?
I want to make my site IE8 compatible. Do I need to do something extra for that?
Update: 6 march 2010
Is there a possibility , I will have to add conditional css for IE8 or it will not needed?
Edited I moved one paragraph and rewrote it based on some feedback.
If you explore http://quirksmode.org you will find compatibility pages that explain the differences between various browsers, including Firefox 3.5 and IE8.
Most likely you will be making changes, but that will depend on what you are using, as there are many similarities, that won't require changes.
All browsers have their various quirks and no browser is guaranteed to display or act the same as another. While W3C is making great strides to expand the functionality that should be standardized, many RFCs are not yet to the Recommendation stage, which is the stage that means it will no longer change and are more likely to be acceptable standards to develop on. Because of this, it is imperative that you ensure your site works in, at minimum, the browsers within your focus group
First, use reset.css. As the page describes, it does a pretty good job of resetting all elements to the standard display format. While not perfect, it gets pretty darn close in all browsers, which is more than you can say without it.
Second, check out QuirksMode to see the various browser compatability with standards (whether those standards are in recommended stage or not). This is where you can decide on the features you will use that match the compatibility with your focus group.
Third, assuming you are on windows (or have a VPC image of it), I recommend installing IE8. Also, check out IE Tester, and install the DebugBar for it (but disable it in IE8), to give you the ability to validate and debug your code in IE 5.5 through IE7. Install any other browsers that you consider in your focus group. Doing so will allow you to test, without question, the appearance on the page.
Using these tools you should be more than able to develop a design that will look 99.9% the same in any browser that supports the features you implement and validate that it is implemented correctly. While it can be a bit daunting, this will greatly reduce the chance of display/js related bug upon release.
Yes, IE 8 still has some rendering bugs. Most of them are fixed, but I think that these for example are still there:
The text-align attribute is applied to block elements, not just inline elements.
Content of elements is still one character high even if there is no content.
Of course it also depends on what doctype you are using. Without a proper doctype the page renders in quirks mode, which pretty much throws the browser back to IE 4.
If you are using different style sheets for different browser/version combinations, you will need another one. IE 8 doesn't behave exactly as any other browser or IE version. I always use a single style sheet for all browsers, and I didn't have to make any changes at all to it to make it work for IE 8.
Expanding on @Kevin's and @James' answers, another good resource is Browser Shots to get screen captures of your site on different browsers and platforms. Very useful for testing browsers/versions that you don't have access to, especially for tricky CSS layouts.
I've used it to view output for Mac and Linux browsers since I work in a Windows-only shop.
Note that the URL must be externally accessible; if you're developing on your local box you'll need to poke a hole through your firewall and maybe setup a dynamic DNS name instead of an IP address.