Dropdown it disappears

Hello. I would like to ask a question about a malfunction. As soon as I click on the dropdown it disappears making the form unusable. Because? Thanks in advance for your valuable advice.
http://johannan.altervista.org/index.php/lista

Hi johnny64,
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If you view the form without the template it is working correctly so I suspect a problem with the template - there are some warning messages from slideout.min.js that might be an indicator of where the problem is.
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Bob

Thanks Bob I will try to use it in a clean installation. See you soon