Nivo Slider display malfunctioning

I have successfully installed and activated StartUp Pro and the provided plugins. I enabled and set up Nivo Slider following the directions precisely. However, the slider is not displaying correctly. The slides appear in two places: one is shoved completely up into the top left corner of the browser window and is then repeated, centered within the page margins, some ways down the page. The remainder of the page content is shoved way down and you have to scroll down quite a ways to see it.

I have not altered the header.php at all and this is a new installation of Wordress, the StartUp Pro theme and Nivo Slider. I have tried disabling all other plugins except Nivo Slider — the problem persists.

The site is installed on a subdomain of my existing website. you can view it—and the problem—here: http://newpch.pc-handyman.net

Hosting is on Hostgator
Wordpress is version 4.8
Plesk is version 5.3.3
Nivo Slider is version 2.5.1

Thanks for any help you can offer