I’m Miles from the Social Care team at Shopify. Editing the gift card to completely personalise it can be done by editing your themes code. If you’re using a free theme from Shopify, then our Support team might be able to help you with this tutorial. Although Shopify can help you with many customizations, some kinds of customizations aren’t supported.
If you’re using a paid theme, then your theme was made by a third-party developer and Shopify’s Support team can’t help you with it. If you need help customizing a paid theme, then consider hiring a Shopify Expert. Similar to free themes, some kinds of customizations aren’t supported because of limitations associated with the theme or Shopify admin.
If you’re comfortable to try your hand at some customisation, I’ve outlined the instructions below. I suggest making a backup copy of your theme in case something breaks when making the changes.
Upload a new image for your gift card
From your Shopify admin, go to Online Store > Themes.
Find the theme you want to edit, and click Actions > Edit code.
In the Assets directory, click Add a new asset: New asset menu
Click Choose File to browse to the new gift card image on your computer and upload it. We suggest using a simple filename, for example, blue-giftcard.png.
Click Upload asset. The new gift card image will appear in your Assets directory. Take note of the file extension (.png or .jpg) Asset list gift card
Edit the gift card template file so that it uses your new image
In the Templates directory, click gift-card.liquid.
The blue border comes from your shop template design. For example, I am using the Streamline template and the background design of images, button, etc is a gray shadow…so that is the background on my gift card preview. Look for that code. Hope that helps or at least leads you in the right direction for a solution.