Datepicker is broken with Form Styles disabled

Due to the fact that the standard Caledera style doesn’t look that well and is partly broken on my site. I decided to disable the Form Style in options and have a 99% good result with it. The only issue I’m facing is that the Datepicker instead of popup box renders itself at the bottom. See picture below. I assume thatthere must be some css conflict between skin and the plugin. Can you help me pointing which part of the code is causing the issue. Thanks

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