See CSS style changes in real-time [on hold]

This isn't so much a coding question than a functionality question. I've seen some CSS tutorial videos where the user has made some CSS changes to the HTML and while refreshing, the style of the page changes in real time. For example, if a block element is on the left side of the screen and you change the CSS to have it on the right, then while refreshing, the element will glide to the right dynamically, rather than having it on the left then after refreshing, it instantly appears on the right.

I'm pretty sure this is the default, but I wanted to change it just for workflow/aesthetic reason to see how the CSS changes.