is it possible to move some of the javascript and css from each html page to files?

[Horizon]

I notice on the nova template, there is quite a bit of javascript and css code in each output html page. Is it possible to move the javascript and/or css to a separate file?

For example the 136 lines of javascript that begins with

Only registered members can view the code.

And below it the 254 lines of css that begins

Only registered members can view the code.

Or is there a reason that those two for example are better to output in each individual html page instead of called with an src for the js or included in a css file that can be cached/optimized?

I suspect the reason may be simplicity of activating/updating plugins...but I'm wondering if there is or could be a tutorial on optimizing the html output by moving those into optimized/cached files.

I'm trying to get a good report on Google Page Speed Insights mobile.