The Search Master app uses the template from your Shopify store theme to display the search results. If the template is too narrow, the search results shown do not take the full width of the page.
But you can resolve this by changing the custom CSS in the Search Master app admin panel. To do so, follow these steps:
Go to Search Master App panel -> Instant Search Widget -> Custom CSS.
Here, you can make the necessary changes. New styles will be applied automatically once you Save the settings.
If you are not able to make the above changes, please reach out to us for support.