Hi,
The plugin only follows the containing element width, by default it is set to 100%. The problem is caused by the fact, that the container is not limited in width below certain resolutions, so it extends to infinity (10 000 pixels).
Based on the site structure and the console, this custom CSS might do the trick:
[html].fl-node-5ad24e4867a69 {
max-width: 100%;
}[/html]
This is not related to the plugin, but I believe it will do the trick for you.