Open Firecode and create a new block. Then jump back to the edit mode tab and add that block to a page. Then open the page in Preview mode.
Now you have three tabs open:
This is great. When changing something in Firecode you'll see the change instantly in Preview mode.
When your website is in development and you click View Website all HTML/CSS code is published and changes are reflected outside of edit/preview mode.
Behind the scenes we have two different files:
Having different files makes it calmer to work. Nothing is visible for visitors outside of edit mode. Then you click Publish/View website to make the changes live.
Tips: If you make a small CSS change and want to publish it live instantly. Open style.scss in Firecode and click the Publish button in the bottom right corner.