title: What is the default width of an HTML table cell <td>?
body: <p>I haven't been able to find the answer to this question: <em>Where in the spec or in UA documentation is the default width of a <code>&lt;td&gt;</code> defined?</em></p>
  
  <p>I've searched the <a href="https://html.spec.whatwg.org/multipage/tables.html#the-td-element" rel="noreferrer">HTML Living Standard</a>, the <a href="http://www.w3.org/TR/html5/tabular-data.html#the-td-element" rel="noreferrer">HTML5 Recommendation</a>, and various other sources.</p>
  
  <p>My understanding (based on usage and observation) is that a table cell will, by default, occupy the full width of the column in which it lives. And the cell cannot be given a different width than the column if other cells exist in the column.</p>
  
  <p>I'm looking for official confirmation of this behavior, preferably in W3C or user agent documentation. But any authoritative reference is acceptable.</p>