So HTML and CSS aren't programming languages. However, as others have said, a natural progression from there is to learn JavaScript if you want to stick to web development. There are tons of JavaScript frameworks and libraries out there, and there will be more in the future.
Java on the other hand (which has nothing to do with JavaScript), is popular on the Android OS world. JavaScript has Java influence, and you can definitely use JavaScript as both object oriented orfunctional as well.
So bottom line, master JavaScript, and jumping to Java won't be as difficult.