Wrong margins between cards in stack-in-card in case of using custom:layout-card

[ildar170975]

Checklist:

• [ x] I updated to the latest version available
• [x ] I cleared the cache of my browser

Release with the issue: 0.2.0

Last working release (if known):

Browser and Operating System: Win10x64, Chrome

Description of problem: The very detailed description is provided here: https://github.com/thomasloven/lovelace-layout-card/issues/184

Javascript errors shown in the web inspector (if applicable): None

Additional information: