Ok, following is the result with your `1px border` suggestion. ![website_themes_rounded_corners_border](https://user-images.githubusercontent.com/617017/60686960-2a66a400-9e9b-11e9...)
I think this is a bit broad border. I tried using a `box-shadow` instead: ![website_themes_rounded_corners_shadow](https://user-images.githubusercontent.com/617017/60686986-49fdcc80-9e9b-11e9...)
Code used: `box-shadow: 0px 0px 3px 1px rgba(0, 0, 0, 0.5);`