What might be causing this strange image overlay in photoslide?

For my work I am working on a test site with Joomla and a slightly modified Quay. I didn't change that much and I sure didn't make any changes to the photoslide part. Stil the overlay, in which the text is displayed, reaches out of the photo. Tried everything to fix it with no effect. Any idea what might be causing this.

The test site is running on siw.activaid.nl and the error is there!