Can't set column widths using datatables in web2py app - datatables

Question

I have used DataTables in several web2py apps with little trouble (after the learning curve), but I am working on a new app and cannot seem to get the columnDefs to set the column widths. Here is the javascript in the page's HTML:
<script type="text/javascript" charset="utf-8">
$(document).ready(function() {
$('#list').dataTable( {
searching: true,
displayLength: 10,
lengthChange: false,
paging: true,
columnDefs: [
{"width": "15%", "targets": 0 },
{"width": "15%", "targets": 1 },
{"width": "10%", "targets": 2 },
{"width": "5%", "targets": 3 },
{"width": "10%", "targets": 4 },
{"width": "10%", "targets": 5 },
{"width": "5%", "targets": 6 },
{"width": "5%", "targets": 7 },
{"width": "20%", "targets": 8 }
]
});
});
All the other options (searching, displayLength, etc.) work as advertised, so I know the function is working, but I've tried about a hundred different things to make the column widths change, to no avail. I get the same lack of response using the columns option, or going back to the legacy aoColumnDefs. There are exactly 9 TH elements and 9 TD elements, so I know there's no mismatch there and there is, in fact, a table with an id='list'. Using Datatables 1.10.11.
Sorry for this seemingly elemental problem; I will appreciate any help or insights as to what I'm doing wrong here.