$('#chatlog').append('<span class="'+colorCode+'">'+newMsg+'</span><br />');
See the /> at the end of the line? Those two characters turn greenish blue, and everything afterwards is just black– it’s like an error almost. No text coloring is present after that point in the document.
If I change it to <br / > (with a space between the / and the >) then it fixes the problem. But what’s causing the problem in the first place?
I’ve never used Gedit, but older html specifications didn’t allow for self-closing tags – you probably just need to tell it what flavor of html/xhtml/html5/whatever. A quick Google search says this is done by selecting the syntax highlighting language at the bottom right. 🙂