Clade
Clade is a folding text editor for Linux and Windows, designed to hierarchically structure any kind of text file and especially source code. It makes navigation through source code faster and easier.
Clade is the successor of Code Browser, it drops links, scripting and keeps only Smalltalk-style navigation, but it adds multi-cursor, line numbers and handles high resolution better on Windows.
Clade is especially designed to keep a good overview of the code of large projects, but is also useful for a simple CSS file. Ideal if you are fed up of having to scroll through thousands of lines of code.
License
Clade is released under the GPL v2 License.