godot/editor/icons/MarginContainer.svg

<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16"><path fill="#8eef97" d="M3 1a2 2 0 0 0-2 2v10a2 2 0 0 0 2 2h10a2 2 0 0 0 2-2V3a2 2 0 0 0-2-2zm0 2h10v10H3zm1 3v4l2-2z"/></svg>