title: Material-UI Autocomplete endAdornment Issue
body: <p>I'm trying to use Material-UI's Autocomplete component in my project.</p>
  <p>I haven't applied any styling to it and it's rendering a bit off.</p>
  <p>I have two issues:</p>
  <ol>
  <li>The highlight over the down around and clearable buttons is not a small circle as shown <a href="https://i.stack.imgur.com/jbNV9.png" rel="nofollow noreferrer">here</a>.</li>
  <li>The dropdown only opens when I click close to the letters E, M and P. I'm assuming this is because of
  the above.</li>
  </ol>
  <p>I'm not sure why that's happening because I just copied the code from Material-UI's documentation and I'm not sure which of my styles, if any, is causing the issue. I also checked on Chrome Devtools and none of my styles are being applied.</p>
  <p>Code Snippet:</p>
  <pre><code>const employees = [
        { name: 'John Oliver' },
        { name: 'Karen Green' },
        { name: 'Alastair Brown' },
      ];
  
      const employeeNames = {
        options: employees,
        getOptionLabel: (option) =&gt; option.name,
      }; 
  
  &lt;div className=&quot;col-lg-5&quot;&gt;
         &lt;FormControl className=&quot;drop-down&quot; required&gt;
            &lt;Autocomplete
              {...employeeNames}
              name=&quot;employee&quot;
              autoHighlight
              renderInput={(params) =&gt; &lt;TextField {...params} label=&quot;Employee&quot; /&gt;}
            /&gt;
            &lt;FormHelperText&gt;Required&lt;/FormHelperText&gt;
          &lt;/FormControl&gt;
      &lt;/div&gt;
  </code></pre>
  <p>Could someone please tell me what the problem is?</p>
  <p><strong>More Screenshots</strong></p>
  <p><a href="https://i.stack.imgur.com/jB6pw.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/jB6pw.png" alt="Screenshot 1" /></a>
  <a href="https://i.stack.imgur.com/n1VHR.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/n1VHR.png" alt="Screenshot 2" /></a></p>
  <p><strong>Update</strong></p>
  <p>I attempted to make a reproduceable sandbox but for some reason my code works correctly over there. No changes whatsoever. It renders how i want it to. What could be the problem then?</p>
  <p><a href="https://codesandbox.io/s/magical-snow-5lxy7" rel="nofollow noreferrer">https://codesandbox.io/s/magical-snow-5lxy7</a></p>