Well since I am a Web Developer myself I have five different browsers. Every browser (well most) reads codes differently. I suggest updating your browser to that latest if it is not already. Also I suggest using a program by the name of HTML-Kit. It is very helpful to many web developers.
It was coded by one of the people that work for the W3 (creators of the World Wide Web).
I suggest also coding in XHTML as it is the future and is much more powerful and easier to understand (my opinion), using the program called HTML-Kit by the click of a button all your coding is in XHTML. So you could code in HTML then transfer to XHTML
To see if your browser is update run this.