If a web page looks all the same on different web browsers and their versions then the web page design is cross browser compatible. The common web browsers are Internet Explorer, Netscape Navigator, Safari, Firefox and Opera. A good web site design will keep the above popular browser in mind for compatibility.
Each one of these browser implements HTML markup language, Java Scripting and CSS differently. Some difference only creates superficial differences other differences can break the web page. Each browser is free to implement “enhancements” to the W3C standard version of each of these formats; hence the matter becomes more complicated.
Computer operating systems or o/s differ way the computer displays graphics and text matter differently. Worse no one can stop the users from using various versions of the web browsers.
So what does the website designer do?
The fact is that full scale compatibility with all web browsers is not possible. But the designer can create web pages using formats and technology such that it works on the most popularly used web browsers and their versions.
Hence it is imperative that the code should be flawless that which conforms to the W3C standard. The code should be validated it is possible to validate the website coding at http://validator.w3.org, here your CSS and links can also be validated at no cost.
A designer should use popular reputed and versatile html editors
Therefore html editors like Macromedia Dreamweaver although one must convert layers to tables to use here. Avoid using Front Page as it is Microsoft specific and is compatible with IE only. The results of Front Page edited html pages may not be good on other website browsers
Other HTML editors will fall between Dreamweaver and FrontPage in cross browser compatibility. SO test the code your HTML editor generates.
CSS Style Sheets
Not all CSS works correctly in different browsers but it does not crash a web browser it makes web pages unreadable sometimes. One of the major CSS problems it causes different block to overlap others and create a jumbled mess. A combination of tables and CSS produces better results.
Flash is great for adding style to a webpage and Macromedia provides flash plug-ins for all of web browsers. Browser for the blind and most handheld devices do not support flash.
Flash is not good from indexing point of view as search engine spiders are not able to read Flash elements on the web pages.
While these are attractive but one must use the alt tag with graphics.
One important point is that website developers should test all web pages on the popular browsers to check for compatibility and redesign accordingly with technology and skills available with them.