Border
The Border and Shadow settings in Shopify allow you to customize the appearance of elements like product cards, buttons, sections, and images by adding borders, rounded corners. These settings help enhance the design and user experience of your store.
Go to Shopify Admin > Online Store > Themes.
Click Customize on your active theme.
In the Theme Editor, click Theme Settings >Border and Shadow

Border
Applies to media elements and content blocks across the theme.
Thickness: Set the thickness of the border.
Corner Radius: Define how rounded the corners appear.
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