title: Change Child element css in TypeScript
body: <p>I have an html like below</p>
  <pre><code>&lt;div class=&quot;DGClass&quot;&gt;
    &lt;div&gt;
      &lt;div&gt;
        &lt;table&gt;
          &lt;tr&gt;
            &lt;td&gt;aasf&lt;/td&gt;
            &lt;td&gt;asf&lt;/td&gt;
            &lt;td&gt;asdf&lt;/td&gt;
          &lt;/tr&gt;
          &lt;tr&gt;
            &lt;td&gt;asdf&lt;/td&gt;
            &lt;td&gt;asdf&lt;/td&gt;
            &lt;td&gt;asf&lt;/td&gt;
          &lt;/tr&gt;
          &lt;tr&gt;
            &lt;td&gt;asdf&lt;/td&gt;
            &lt;td&gt;asdf&lt;/td&gt;
            &lt;td&gt;asf&lt;/td&gt;
          &lt;/tr&gt;
        &lt;/table&gt;
      &lt;/div&gt;
    &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  <p>I Change second row's, second column's background. This is my css code</p>
  <pre><code>.DGClass  *  tr:nth-child(2) &gt; td:nth-child(2)   {
      background-color: red !important ;
  }
  </code></pre>
  <p>But I want to change cells background color by <strong>parameter</strong> in TypeScript. How can I do that?</p>