title: html/css how to put border on thead tr
body: <p>I want to put a border on the bottom of <code>tr</code> of <code>thead</code>.</p>
  
  <p>I have table like below. I was able to put border on bottom of <code>th</code>s. However, this is short of what I wanted, because where two borders across each other is still not black as shown in the image below.</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>table {
      border-collapse: collapse;
  }
  table thead tr th {
    border-bottom: 1px solid #000000;
  }
  
  table th,
  table td {
    border: 1px solid #d9d9d9;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;table&gt;
    &lt;thead&gt;
      &lt;tr&gt;
        &lt;th&gt;
          #
        &lt;/th&gt;
        &lt;th&gt;
          Date
        &lt;/th&gt;
      &lt;/tr&gt;
    &lt;/thead&gt;
    &lt;tbody&gt;
      &lt;tr&gt;
        &lt;td&gt;
          TUB1234
        &lt;/td&gt;
        &lt;td&gt;
          2018/02/22
        &lt;/td&gt;
      &lt;/tr&gt;
    &lt;/tbody&gt;
  &lt;/table&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p><a href="https://i.stack.imgur.com/J9EFs.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/J9EFs.png" alt="enter image description here"></a></p>