Pictures don't show in slider or blank widget of Wowchemy

I want to add pictures to a slider widget on my home page, but they don’t show up on my website. I’ve put the pictures in the static/media folder. I also tried the following modifications:

  • change the widget into a blank page
  • add a png-picture instead of a jpg
  • change the extension from .jpg to .JPG
    all without results. The text overlay do show up. Any suggestions?

The website is on: GitHub - koenraadvanmeerbeek/Website