How do I set the column width of some column width in datatables

My experience is that columns.width mostly is suitable for relative intents, i.e "I want this column to be relatively larger". There is a lot that can inflict on each column width, and even if you carefully target each column with an exact percentage that add up to 100 you end up frustrated.

If you want exact, precise column width definitions there is no way around hardcoded CSS :

table.dataTable th:nth-child(1) {
  width: 20px;
  max-width: 20px;
  word-break: break-all;
  white-space: pre-line;
}

table.dataTable td:nth-child(1) {
  width: 20px;
  max-width: 20px;
  word-break: break-all;
  white-space: pre-line;
}

http://jsfiddle.net/6eLg0n9z/