Ideally, you will need just a single set of Cascading Style Sheets (CSS) for the website that you have created and those styles are likely to work for every browser that people use. But this, as every web guru will tell you, is nothing more than a pipe dream. The contemporary web browsers do not have standard levels of implementation for the style sheets. To add to the woes, the implementation is often very buggy. Even if you try to find solutions to these problems, you get to see that your potential customers are mostly using older browsers that hardly support present CSS standards.
In fact, this uneven support in specific browsers is the only issue that needs to be dealt with, at present. The dilemma is that different browsers have their own ways of interpreting Cascading Style Sheets commands differently, causing much consternation among web designers who may decide to switch back to table layouts which are more accurate in pixel description.
In such circumstances, the webmasters prefer specifications regarding a particular style sheet as to which browser would support a particular set of CSS codes. Besides that, they also need to hide other style sheets from the older browsers.
Cross browser compatibility is a colossal issue when it comes to the development of websites which are undergoing browser testing. However, most web surfers are using Internet Explorer and Firefox these days. At times different versions of the same browser yield different output, like the display in IE8 is quite different from IE6. To handle this issue, you need to use different CSS for different browsers.
The problem is that there is no such standard method to exclude or even include the Cascading Style Sheets from being used by a particular website in the World Wide Web.
Thankfully, there are a number of tricks and tactics to settle the problem. These tactics and workarounds may not be standard ones, but these are documented methods that a web developer can readily use to include style sheets in some specific browsers only. The workarounds usually rely on the common bugs, the ones that are already known in certain specific versions of the browsers.
However, these workarounds and tricks might also backfire, as there are few browsers that you might want to code for, but you do not have adequate means to detect them or workaround with them.