I would suggesting using ‘Vim’ or ‘gVim’ for editing your files.
https://www.vim.org/ There are versions available for every major OS and then some.
It includes syntax highlighting and all kinds of other features you’ll never need. I use it in conjunction with Filezilla to edit files. You can set up Filezilla to open files with certain programs (such as gvim) and then edit the file locally. Upon closing/saving the file in Vim you’ll have the option to automatically upload it to your server.
