I am sorry I was not clear enough.
The problem of the widget is SOLVED! Thanks for that!
The display of the bootstrap slider on mobile device is still a problem.
Please check how it should look like (www.web-aid.nl as example)
Please check how it is looking now on en.web-aid.nl
You helped me previously for this issue for web-aid.nl & web-aid.fr a month ago, but the code you gave me for solving this issue is not working on en.web-aid.nl.
Hope to hear your solution!