title: How do I get chrome.tabs.insertCSS to work?
body: <p>So I've been making a random fun chrome extension, and I've been trying to get chrome.tabs.insertCSS to work but it just won't. chrome.tabs.executeScript works fine, but insertCSS will not. This is what I have right now:</p>
  
  <pre><code>var txt = document.querySelector('#datapodtxt');
  var img = document.querySelector('#datapodimg');
  chrome.tabs.executeScript(null, {file: "content.js"},function() {
      if (chrome.extension.lastError) {
          txt.innerText = "Error with page";
          img.src=chrome.extension.getURL('datapodblocked.jpg');
      } else {
          txt.innerText = "Datpodified your page";
                  img.src=chrome.extension.getURL('datapod.jpg');
      }
  });
  chrome.tabs.insertCSS(null, {file: "inject.css"});
  </code></pre>
  
  <p>It's just the last line which won't work, and I've tried a number of different things, but nothing happens.
  (all that inject.css is in case you need it):</p>
  
  <pre><code>body {
    background-image: url("datapod.jpg") !important;
  }
  </code></pre>