Demo Locally Created Pages As Posts

I would like to demo webpages that I create locally as posts on my blog. I thought that I would be able to paste the javascript and css in the demo.html file and then paste that into a new blog post. That is the not the case, for me at least.

For example, I created a simple calculator on my local machine. I would like to display that on my blog. I know tons of people do this but I don’t know how.

I’ve made sure that the demo.html file works locally with the js and css embedded internally to the demo.html file. Even in the text editor white space matters. <p> tags were added around chunks of code. I just don’t know what to even search for on the forums.

Can anyone help?