http://schrodinger.github.io/fixed-data-table-2/example-styling.html
In the table displayed on this dataTable demo page:
1 - try adding 1px black solid border-bottom on .public_fixedDataTableRow_main element (it's basically a row of the table); you'll be able to see the border.
2 - now make the border-width 0.99px, i.e. .99px black solid, the border won't be displayed.
And this happens only in IE! Works fine in Chrome, Safari and Edge.
P.S. while debugging, I reached to the point where removing CSS transform property from .fixedDataTableCellGroupLayout_cellGroup el, (a child of the row element itself) made the border appear (.99px) within that cell's bottom.
Edit: when using border-width .99px, the border is there, it is simply displayed under the div's children (even though overflow:hidden and box-sizing:border-box is given). Now as soon as it is made 1px, it recognises the overflowing children and hides that much part of it so that the border is then visible.