I see that it has top:1001 when I inspect the element, but I don’t know where it gets it from
Hi, that’s a strange effect. It looks like the script has trouble calculation of the viewport height, effectively placing it out of center. Then scrolling seems to add to the actual page body height which I suspect is a conflict with another script.
The errors I notice that must be fixed before all else are:
1. missing bootsrap.js
2. missing and skin.css (from ubermenu)
3. the following lines at the top of the source must be removed:
<link rel="stylesheet" type="text/css" href="http://www.xelion.nl/wp-content/cache/minify/000000/VY7RDsIwCEV_SII--TmmRVQMbWehLvt7m7ot2QMv9xwunDE2k8xm0IezS1CDeULzRfl0QW-Rp9oZWiVMQTLOHJF6sKOuUckeyOFRaoIrSiZtd7bhjaohVQ4uX7BC_cxRWtkfwb7y_jSuC1BRDZMxFEhdI1R5vvy2PZnYuVQwla3ukPwA.css" media="all" />
<link rel="stylesheet" type="text/css" href="http://www.xelion.nl/wp-content/cache/minify/000000/M9QvKijWzcxNTE_VTU_MyUktqtRPSS1IzUtJzUvOTC3WT0vMS65Myq_QzyosBUrqwfi6hnrGeiYA.css" media="all" />
<link rel="stylesheet" type="text/css" href="http://www.xelion.nl/wp-content/cache/minify/000000/hY9NDsJACIUvJDNpXHgenNJKO38OmDq3l0RrTLpwAYHHywcMvlUBTjgTzBgjtX5UToPXjVWpgTYMKzVPqSz8zjZNyDHcOFWYSoOtehQhFR_E4kZhvZanS5zNitnQSiCRR-P8GKdWsv6BmZI-IELpMGEO3eD-Wyz3h13s9h4Gd3aXfXetMLLUiB2q_XcQQLRHkhc.css" media="all" />
<link rel="stylesheet" type="text/css" href="http://www.xelion.nl/wp-content/cache/minify/000000/M9RPyS_Py8lPTNHNzc_LLMkv0i9ITE_VTUxJyc_TLy6pzEktBgA.css" media="all" />
<link rel="stylesheet" type="text/css" href="http://www.xelion.nl/wp-content/cache/minify/000000/VYtLCoAwDEQvZAhdeKDUDBhIrfQj9PYW6sbdzLw3gRPUhOBIuBqdLflOjykyyaUkXS3T7TJQlvqZv7L4FrhHlDl0rm2-pegMw1E5SrXjBQ.css" media="all" />
in fact, the DOCTYPE tag must be the absolute first thing in the source a browser gets to read. Strictly speaking there must not even come a blank line or space before it.
Plus it looks like you hardcoded dynamic W3TC minification URL’s. Do not do that.
If the issue remains, please deactivate Minification in the W3TC setting. This might at least make debugging possible.
