button missing in featured content slider in iphone browser

Hello everyone just another question I could not solve. I am using the featured content slider. Using a normal browser all is working well. But using the iPhone browser the image of the post with the excerpt is displayed but the button is missing. That wouldn't be serious if the whole image would be a link to the post. But as the button is the link to the post its a bad user experience. If you like have a look at https://lisseck.com