Problems pasting styled HTML tables into Microsoft Word

This is what it looks like in a browser: Browser Here is the fiddle. As far as I am aware there is nothing wrong with this HTML / CSS structurally. Yet, if I select the content and paste it into Microsoft Word 2016: Word The columns are not consistent. Why is this?

Update

I also noticed the Time column on the left is inconsistent. In each of my table objects I was using a colgroup :

What I thought I was try was duplicate the width properties from the above classes into each of my cell classes, like this:

.cellTime < padding-left: 3mm; padding-right: 5mm; font-size: 9pt; font-weight: 700; color: gray; width:7%; >.cellTheme < border-right-style: none; >.cellPosition < color: gray; padding-right: 2mm; text-align: right; font-size: 8pt; font-weight: 700; vertical-align: middle; text-transform: none; border-left-style: none; width:10%; >.cellName

Word 2

This is improved:

The right hand column is all good.
Most of the left hand column is good (just not the very top)

So it seems that Word does not obey the colgroup object when establishing the styling of the table cells.