微件:FixTableHeader

<style>

1. fixed-table-header { background-color: white; }

</style><script> window.onscroll = function() {

   var tables = document.getElementsByClassName("fix-table-header");
   var hdr = document.getElementById('fixed-table-header');
   for (var i = 0; i < tables.length; ++i) {
       var table = tables[i];
       var rect = table.getBoundingClientRect();
       if (rect.top < 0 && rect.bottom > 0) {
           if (hdr == null) {
               hdr = table.cloneNode(true);
               hdr.id = 'fixed-table-header';
               hdr.style.position = 'fixed';
               hdr.style.pointerEvents = 'none';
               hdr.style.top = 0;
               hdr.style.width = table.style.width;
               table.parentNode.appendChild(hdr);
               hdr.style.visibility = 'hidden';
               for (var i = 0; i < hdr.childNodes.length; i++)
                   if (hdr.childNodes[i].tagName == 'THEAD') {
                       hdr.childNodes[i].style.visibility = 'visible';
                       hdr.childNodes[i].style.pointerEvents = 'auto';
                   }
           }
           return;
       }
   }
   if (hdr != null) hdr.remove();

} </script>