Is the website rendering OS dependent?

I'm developing a very si开发者_StackOverflow社区mple web site, with only one web page, but i need the one single page to look as it should in all the browsers. Now, for testing purposes, i have installed a bunch of web browsers on my windows 7 machine (FF, Chrome, Opera, Safari, Netscape etc.) and after doing some markup changes, i've got the same looking webpage on all the browsers.

Now the question is, does "the way" a browser renders a web-page depend on the operating system the browser is running on? Should I install linux (or other os) and test again or it will just be fine?

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You should definitely be testing sites cross-platform, others may disagree, but the rendering is definitely different.

In addition to base-rendering, you may also be missing fonts, have alternate fonts with the same name, have anti-aliasing enabled/disabled on different platforms/configurations and much more.

To see exactly what I mean, on a base install of Windows 7 with Firefox 5, OSX with Firefox 5 and Linux with Firefox 5, when using the font 'Arial' or 'Verdana', you will clearly see the differences, even if those fonts do exist on all platforms.

On top of the differences you'd see above, even your positioning could be out if you're using non-absolute values (hell, even if you are using absolute values such as px it could be out!), so it's always best practice to check your sites cross-platform, it's as important as checking cross-browser, in my opinion.

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Even if the same fonts exist on different OS they might look different.

So yes if you want to be sure that the page look satisfactional on the OS you should test..

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As rudi_visser said, you should be doing cross-platform testing. It's a bit of a bother, but absolutely worth it.

You can start by using a service like browsershots.org to quickly check if your site looks ok. To check older versions of IE, Microsoft provides some virtual machine images you can run in Virtual PC to really test the sites. Alternatively, there's this site which is like browsershots.org, only faster and IE-only. Please note, that screenshot services are no substitute for actually testing the site on a certain platform/browser, but it's a quick way to see if something's working at all.

I would definitely recommend checking your site in the older versions of IE, since IE has a rich history of, well, not working quite right. IE9 (which I assume you're using) is a big improvement, but a lot of people are still on versions 6-8. Since IE6 was around for ~9 years without major changes, IE 7, 8 & 9 have each had a lot of catching-up to do, so they're all very different.

As for other browsers, their rendering is more consistent across versions, but they may not be consistent across platforms. Again as rudi_visser said, elements might shift around, and especially text can look different. For instance, Mac OS X uses a different font-smoothing technique from Windows, so a line of text may appear longer/shorter, bolder/lighter from one to the other. A cross-platform browser like Firefox will use the OS' font-rendering, so even though the browser's the same on the different platforms, it can still look different. (The exception is Safari on Windows, which, I think, insists on using Mac-like font-smoothing instead of Windows' own).