title: CSS border-width thrashing
body: <p>I have been thrashing like crazy -- literally days -- trying to highlight certain parts of my table with thicker borders.</p>
  <p>I have a 12-row x 3-column table that has a header row and two &quot;label columns&quot; making it a 13-row x 5-column table altogether.</p>
  <p>It looks like this:</p>
  <p><img src="https://i.stack.imgur.com/cf8OW.png" alt="my 13x5 table" /></p>
  <p>I would like for all the borders to be 1px but I would like to highlight the 12 3x1 &quot;boxes&quot; by making their borders, say, 3x. I have shown the borders of those &quot;boxes&quot; in red to better illustrate their location, but I would like them to be black borders. I would also like to make the outside border of the table 3px and maybe the horizontal borders that run the full width of the table.</p>
  <p>I have been trying to use the :nth-child(3n+m) selector to facilitate this:</p>
  <pre class="lang-css prettyprint-override"><code>table,
  th,
  td {
    border: 1px solid black;
    border-collapse: collapse;
    padding: 2px;
  }
  tr: nth-child(3n+2) {
    border-style: solid;
    border-width: 3px 3px 1px 3px;
  }
  tr: nth-child(3n+3) {
    border-style: solid;
    border-width: 1px 3px 1px 3px;
  }
  tr: nth-child(3n+4) {
    border-style: solid;
    border-width: 1px 3px 3px 3px;
  }
  </code></pre>
  <p>My plan was to make</p>
  <ol>
  <li>the 3n+2 elements heavy except on the bottom,</li>
  <li>the 3n+3 elements heavy on the left and right, and</li>
  <li>the 3n+4 elements heavy except on the top</li>
  </ol>
  <p>Right now, <strong>none</strong> of the borders are getting 3px :-(, but last night, the correct horizontal borders were getting 3px, but the only vertical borders that were 3px were the far left and far right.</p>
  <p>I thought I might be able to do some column elements and get the vertical borders, but I need to crawl before I can walk here.</p>
  <p>Can you override previous border-width assignments with subsequent assignments?</p>
  <p>Thank you in advance.</p>