html,
body {
  margin: 0px;
  padding: 0px;
  background: lightgray;
}
canvas {
  display: block;
  width: 320px;
  height: 320px;
  padding:20px;
}
.center {
  position: fixed;
  top: 50%;
  left: 50%;
  margin-top: -185px;
  margin-left: -185px;
  /* border: 10px solid black; */
}
.shadow {
  -webkit-box-shadow: 0px 0px 12px 0px rgba(0, 0, 0, 0.75);
  -moz-box-shadow: 0px 0px 12px 0px rgba(0, 0, 0, 0.75);
  box-shadow: 0px 0px 12px 0px rgba(0, 0, 0, 0.75);
}
/* .inner-shadow {
  -webkit-box-shadow: inset 0px 0px 8px 0px rgba(0, 0, 0, 0.5);
  -moz-box-shadow: inset 0px 0px 8px 0px rgba(0, 0, 0, 0.5);
  box-shadow: inset 0px 0px 8px 0px rgba(0, 0, 0, 0.5);
} */
#main_body {
  margin-top: 20px;
  background: lightgray;
}
iframe {
  padding: 0;
  margin: 0;
}
.art-frame {
  height: 420px;
  width: 420px;
  border: 0px;
}
.container {
  display: flex;
  flex-flow: row wrap;
  justify-content: center;
}

.thumbnail {
  top: 50%;
  left: 50%;
  margin-top: -185px;
  margin-left: -185px;
  /* border: 10px solid black; */
  -webkit-box-shadow: 0px 0px 12px 0px rgba(0, 0, 0, 0.75);
  -moz-box-shadow: 0px 0px 12px 0px rgba(0, 0, 0, 0.75);
  box-shadow: 0px 0px 12px 0px rgba(0, 0, 0, 0.75);
  width: 360px;
  height: 360px;
  display: block;
  position: relative;
}

.thumb_iframe_pair {
  width: 420px;
  height: 420px;
}