<head>
<style>
blockquote {
  margin:0;
  margin-right:revert;
  margin-left:revert;
  border:1px solid black;
}
</style>
</head>
<body>
<blockquote id="quote">This blockquote should have user agent margins for the left and right but the top and bottom margins should be 0.</blockquote>
<blockquote id="quote">This blockquote should have user agent margins for the left and right but the top and bottom margins should be 0.</blockquote>
</body>
</html>