title: text-align:center is not working on Apps Script HTML sidebar
body: <p>So I am making an HTML sidebar in Google Sheets using Apps Script. I am also using the Skeleton CSS framework.</p>
  <p>So I'd like the submit button here to be centered:</p>
  <p><a href="https://i.stack.imgur.com/rXvuK.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/rXvuK.png" alt="Sidebar" /></a></p>
  <p>I've tried this: making an align class in CSS, and then applying it to the button. I forgot to mention that all my other elements are aligned except the buttons.</p>
  <pre class="lang-css prettyprint-override"><code>  &lt;style&gt;
      body{
        background-color: white; 
        color: black; 
      }
      .align{
        text-align: center; 
      }
      .margin{
        margin-bottom: 10px; 
      }
      h1{
        font-size: 20pt; 
      }
  
      h2{
        font-size: 16pt; 
      }
  
      &lt;/style&gt;
  </code></pre>
  <p>Here is my HTML code:</p>
  <pre class="lang-html prettyprint-override"><code>  &lt;body&gt;
      &lt;h1 class = &quot;align &quot;&gt;Welcome to the clothing expense custom menu bar!&lt;/h1&gt;
      &lt;h2 class = &quot;align&quot;&gt;Here are the custom functions you can use:&lt;/h2&gt;
      &lt;p class = &quot;align&quot;&gt; See how much you've spent on a brand.&lt;/p&gt;
      &lt;form onsubmit=&quot;runFunc()&quot;&gt;
        &lt;input class = &quot;u-full-width &quot; id=&quot;brand&quot; type = &quot;text&quot; placeholder=&quot;Enter brand name&quot;&gt;
        &lt;div&gt;
          &lt;button type=&quot;submit&quot; class=&quot;button-primary align&quot;&gt;Submit&lt;/button&gt;
        &lt;/div&gt;
      &lt;/form&gt;
  
  
      &lt;p class = &quot;align&quot;&gt; See how much you've spent on a type of clothing.&lt;/p&gt;
  
      &lt;form onsubmit=&quot;runFuncTwo()&quot;&gt;
        &lt;input class = &quot;margin u-full-width&quot; id=&quot;type&quot; type = &quot;text&quot; placeholder=&quot;Enter clothing brand&quot;&gt;
        &lt;div&gt;
          &lt;button type=&quot;submit&quot; class=&quot;button-primary align&quot;&gt;Submit&lt;/button&gt;
        &lt;/div&gt;
      &lt;/form&gt;
    &lt;/body&gt;
  </code></pre>
  <p>Thanks!</p>