If you decide to alter your design, you may want to preview the new theme to see what your store would look like. To do so, navigate to Admin > Configuration > Themes and click on the Preview button of the desired theme.
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The front end of your store will now be shown in preview mode. When you are in preview mode, there is a little symbol displayed on the left side of the browser window. By clicking on it, you can switch the themes and stores of your shop within preview mode.
