jquery.floatThead.js - test for issue: https://github.com/mkoryak/floatThead/issues/100
Issue #100
when scrolling down, the header overlaps the thick top border of the container
position: 'fixed'
Header1-2 header3
Header1-2 header3
Cell1Row1 Cell2 Cell3
Cell1Row2 Cell2 Cell3
Cell1 Cell2 Cell3
Cell1 Cell2 Cell3
Cell1 Cell2 Cell3
Cell1 Cell2 Cell3
Cell1 Cell2 Cell3
Cell1 Cell2 Cell3
Cell1 Cell2 Cell3
Cell1 Cell2 Cell3
Cell1 Cell2 Cell3
Cell1 Cell2 Cell3

position: 'absolute'
Header1-2 header3
Header1-2 header3
Cell1Row1 Cell2 Cell3
Cell1Row2 Cell2 Cell3
Cell1 Cell2 Cell3
Cell1 Cell2 Cell3
Cell1 Cell2 Cell3
Cell1 Cell2 Cell3
Cell1 Cell2 Cell3
Cell1 Cell2 Cell3
Cell1 Cell2 Cell3
Cell1 Cell2 Cell3
Cell1 Cell2 Cell3
Cell1 Cell2 Cell3