Your business will need to contact Punchh support or your Customer Success manager in order to implement the below CSS.
In order to automatically resize your Hero Images for Rich Messages you will need to include and remove the follow sections of code in your CSS:
You will need to replace this section CSS:
{
"key": "hero_content",
"type": "image"
}
With THIS:
{
"key": "hero_content",
"type": "image",
"resizeMode": "cover"
}