Like Shopify, you have the option of a wide range of themes, but only seven are free. They are divided into categories, are fully customizable and responsive. You can edit the themes and customize them to mobile devices, including phones and tablet screens. If you opt for the premium themes, be ready to part with almost 300 dollars for one.
Bigcommerce has the merchandising tool, Store Design, which allows you to edit your theme without needing to switch from one place to another. You, therefore, have more control over how your site will look because the editing is so much simpler now.