Before clicking 'Save' when creating or editing your Website page, you can use Craft CMS's live preview tool to preview your changes in the same way that they would appear live.

When creating or editing your page, click the 'Live Preview' button on the right hand side.

Once you've clicked 'Live Preview' a preview will appear to the right and your editing options will remain on the left so that you can continue to make changes and see them within the preview screen.

From here, you can either click the 'Close Live Preview' button to continue editing your page, or click 'Save' if you're happy with all of your changes.