Color Style multi-language sections in one program?

Hey guys,
First time posting on here, so cutting to the chase:
I am an undergraduate research tech writing a program for one of our systems at UMKC.
The program often uses multiple languages in one program, now my question is this;
If the first third of my program is written in HTML, the second portion of the program in Javascript and the third in CSS, etc… is there a way for me to change the syntax styling of select ‘chunks’ of code? I tried simply highlighting a section, changing the text style, but clearly that didn’t work. If there’s a way to do this, this would make my life so much easier with this project. If not, any recommendations on how I can more easily organize everything?

HTML, CSS, and JavaScript are normally kept in separate files, and Atom highlights by file, not by project (or “program”), so this shouldn’t be a problem. In cases where JS and CSS are embedded in HTML files via script and style tags, Atom’s highlighting engine is capable of identifying that and using different highlighting rules than the ones that govern the rest of the document.