I'm in the process of creating .chm files and was curious to know if these options are available?
Of course you can use CSS. JavaScript not in all cases. See HTMLHelp - Linking.
Make sure your design.css is inside you project level structure and added to the [FILES] section of your HHP project file. You can open this *.hhp file with e.g. Notepad++ to add files. If the files are listed in the [FILES] section the compiler includes them to the CHM file.
[FILES]
welcome.htm
design.css
First_Steps\download.htm
First_Steps\starting_program.htm
How_to_extend\extend_menu.htm
How_to_extend\power_function.htm
images\gui_screenshot.jpg
来源:https://stackoverflow.com/questions/43942102/html-help-workshop-is-it-possible-to-use-css-or-javascript-within-a-chm-file