Preview the final version of your site without having to deploy it. When previewing you can explore and click around your site just like you will be able to after it's deployed. This will allow you to check every detail of your site before you go public. 

Press the play button at the top right of the editor to exit the editor and preview your site.

Click the play button again to return to the editor from previewing your site.

You can view how your site looks on different devices using the dropdown to the right of the play button. This dropdown only appears once you are already previewing your site.