Benefits of php open source
1. Open source and free, one of the biggest reasons to choose PHP is that it reduces development costs by up to 2/3rds of proprietary languages. The software required to run PHP is also freely available and open source, further reducing running and operation costs for years to come.
2. Ready made frameworks, huge libraries of pre-written code and dedicated team of global contributors means that many functions that you may require can easily be included from pre-written code. The ready made frameworks like Symphony, PHPCake and Code Ingnitor speed up development time, getting your website to the market quicker and at a much lower cost.
3. PHP is a purpose built language for the internet. It is specifically designed to run on web servers to deliver dynamic web pages as quickly as possible, even on extremely high traffic websites.
4 Constantly evolving to meet the demands and requirements of the modern day world wide web, PHP is regularly updated to include new features, code optimization and overall stability and performance enhancements. Since PHP is also open source, you don't even have to pay to get these updates, it's all free.
5. PHP is a tried and tested language for the internet. It's over 10 years old and is used on everything from banking to social network websites. Some of the biggest players who use PHP include Yahoo and Facebook. Even companies like IBM make use of PHP.

Yeah ! PHP and CSS give good look to website.