Sending (Emailing) HTML and CSS File

Course:Build a website with HTML, CSS and Github Pages
Language:HTML and CSS
Currently taking the above course and building a webpage for work as I go .
I have an HTML and CSS file on my local machine that is linked .
Question: What is the best practice for me to email the files to someone where it displays both style and mock-up for the web page to the person I am emailing it to ?

Probably the easiest way to send HTML/CSS is as TXT attachments (make copies, change the extension, and attach to your message).