HTML 5 and CSS 3 are indeed languages that are processed by a web browser (client side), therefore the hosting server (server side) doesn't render, parse, or execute any kind of HTML 5 or CSS 3 code. But other posters have already mentioned this.
If you are a new web programmer, I submit this concept to you: "graceful degradation". Since as a web programmer you have zero control over what kind of browser your end user uses, it is beneficial to plan your shots. HTML 5 and CSS 3 are emerging technologies that have varied levels of support across the various web browsers available to the public. Graceful Degradation means that you want to use HTML 5/CSS 3 technologies, and you implement them but you leave methods/means for your users to still interact with your website if those technologies are not supported by the browser they are using.
Here are some links to articles that might be useful to you in learning about how to make your page/website perform Graceful Degradation:
Article 1,
Article 2,
Article 3
Alternatively there is another idea that also corresponds to this concept, known as "Progressive Enhancement". I'm just going to quote the wikipedia entry:
In Progressive Enhancement (PE) the strategy is deliberately reversed: a basic markup document is created, geared towards the lowest common denominator of browser software functionality, and then the designer adds in functionality or enhancements to the presentation and behavior of the page, using modern technologies such as Cascading Style Sheets or JavaScript (or other advanced technologies, such as Flash or Java applets or SVG, etc.) All such enhancements are externally linked, preventing data unusable by certain browsers from being unnecessarily downloaded.
Good luck!
H