HTML table widths set proportionally

As mentioned by Itay, the total width has to match the width of the table. When you set the width of one column the only thing that happens is that first column takes 5% and the other ones take remaining 95%, if you add width to all, they split the space piece by piece until they reach 100%.

One way you could get what you're trying to achieve is have an empty column like this

table {
  table-layout: fixed;
  width: 120px;
  border-collapse: collapse;
  background: whitesmoke;
}

td {
  overflow: hidden;
  white-space: nowrap;
  text-overflow: ellipsis;
  padding: 0;
}

td:first-child {
  width: 5%;
}

td:nth-child(2) {
  width: 2%;
}

td:last-child {
  width: auto;
}

<table>
  <tr>
    <td>Ed</td>
    <td>Wood</td>
    <td></td>
  </tr>
  <tr>
    <td>Albert</td>
    <td>Schweitzer</td>
    <td></td>
  </tr>
  <tr>
    <td>Jane</td>
    <td>Fonda</td>
    <td></td>
  </tr>
  <tr>
    <td>William</td>
    <td>Shakespeare</td>
    <td></td>
  </tr>
</table>

That way, the empty column will be taking that remaining space and let your other columns have the width you specified. And if you do decide that you want the rows to span the full width of the table, width: auto will be 0 and shouldn't cause you any problems.