Cross platform web designs are easily mapped on different platforms. Cross-platform Web applications help designers as reuse blocks, resulting in poor performance, poor scalability, and poor usability. Furthermore, the designer may "reinvent the wheel" when attempting to implement the same design for different platform. Patterns are used for mapping a Web design to new platforms while maintaining its quality attributes. In these type of designs, Microsoft and Netscape dHTML methods are used with style sheets and scripting languages. It offers browser interoperability fastly. Cross browser design requires a good understanding of the Document Object Model and Java Script methods.