Node's teaser view mode has extra "panels-default" markup/wrapper/classes I'm using bootstrap 3 as basetheme and Physics as main.
On content types view mode (teaser) I've created a Horizontal tabs group and added 3 Horizontal tab containers under it.

The problem is that content inside Horizontal tab is wrapped with Bootstrap panel markup which creates unnecessary borders and shadows. I can't find that where this is defined.

And since Horizontal tabs and Horizontal tab aren't part of either themes or supporting modules it seems weird that content is wrapped in any bootstrap markup.

Result

View mode/containers setup

UPDATE

The question is that why are these fields wrapped with a bootstrap panel markup?
Copy bootstrap-panel.tpl.php from base to main and configure it per requirements.