[解決済み] CSS3 トランスフォーム 片方だけ傾ける

.container {
  overflow: hidden;
}

#parallelogram {
  width: 150px;
  height: 100px;
  margin: 0 0 0 -20px;
  -webkit-transform: skew(20deg);
  -moz-transform: skew(20deg);
  -o-transform: skew(20deg);
  background: red;
  overflow: hidden;
  position: relative;
}

.image {
  background: url(http://placekitten.com/301/301);
  position: absolute;
  top: -30px;
  left: -30px;
  right: -30px;
  bottom: -30px;
  -webkit-transform: skew(-20deg);
  -moz-transform: skew(-20deg);
  -o-transform: skew(-20deg);
}

<div class="container">
  <div id="parallelogram">
    <div class="image"></div>
  </div>
</div>