title: How do I remove an injected CSS file?
body: <p>I use <code>chrome.tabs.insertCSS(null, {file: "style.css"});</code> to insert a css file into the page, and it works fine. </p>
  
  <ul>
  <li>But is there a way to remove the file?</li>
  <li>Also, if I inject another file named <code>style.css</code>, does it override the first one?</li>
  <li>And by the way, where can I see the injected CSS files? Scripts can be viewed in "Sources/Content Scripts" (of chrome developer tools), but I cannot find the CSS files.</li>
  </ul>