Responsive horizontal navbar won't respond

[ailrox]

Alright. So I'm attempting, quite unsuccessfully, to make the navigation bar at the top of my page to be the full width of whatever screen it is being viewed on. It's one of those simple navbars you can find tutorials on everywhere.

 

(If I get some of the lingo wrong here, feel free to correct. I'm still learning.)

ul {list-style-type:none; margin:0; padding:0; overflow:hidden;}li {float:left;}a:link,a:visited {display:block; width:120px; font-weight:bold; color:#FFFFFF; background-color:#98bf21; text-align:center; padding:12px; text-decoration:none;}a:hover,a:active {background-color:#7A991A;}

<ul><li><a href="home">Home</a></li><li><a href="portfolio">Portfolio</a></li><li><a href="services">Services</a></li><li><a href="contact me">Contact Me</a></li></ul>

I'd appreciate any sort of help.