Mystery box #2

Slightly less mysterious version of this mystery box.

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<style>

body {
  margin: 0;
  padding: 0;
}

.container {
    width: 300px;
    height: 500px;
    margin: 100px auto 0 auto;
    position: relative;
    perspective: 2000px;
    -webkit-perspective: 2000px;
}

.cube {
    position: absolute;
    width: 100%;
    height: 100%;
    transform-style: preserve-3d;
    -webkit-transform-style: preserve-3d;
    animation: spin 5s infinite linear;
    -webkit-animation: spin 5s infinite linear;
}

.questionmark {
  position: absolute;
  width: 300px;
  height: 300px;
  pointer-events: none;
  background: url("data:image/svg+xml;base64,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") no-repeat center center;
  background-size: 178px 171px;
  animation: spin 5s infinite linear reverse;
  -webkit-animation: spin 5s infinite linear reverse;
}

.side {
  margin: 0;
  width: 300px;
  height: 300px;
  position: absolute;
  cursor: pointer;
}

.side > * {
  border: 0;
  display: block;
  position: absolute;
  width: 100%;
  height: 100%;
}

iframe {
  opacity: 0;
  overflow: hidden;
}

.hidden {
  display: none;
}

.side > div {
  background-image: url("data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHdpZHRoPSI1MCIgaGVpZ2h0PSI1MCI+CjxyZWN0IGZpbGw9InJnYmEoMjU1LDI1NSwyNTUsMC4yKSIgc3Ryb2tlPSJub25lIiB4PSIwIiB5PSIwIiB3aWR0aD0iMjUiIGhlaWdodD0iMjUiPjwvcmVjdD4Kd2lkdGg9JzUwJyBoZWlnaHQ9JzUwJyZndDsKPHJlY3QgZmlsbD0icmdiYSgyNTUsMjU1LDI1NSwwLjIpIiBzdHJva2U9Im5vbmUiIHg9IjI1IiB5PSIyNSIgd2lkdGg9IjI1IiBoZWlnaHQ9IjI1Ij48L3JlY3Q+Cjwvc3ZnPg==");
  pointer-events: none;
}

.cube {
  transform: translateZ(-100px) rotateX(-90deg);
  -webkit-transform: translateZ(-100px) rotateX(-90deg);
}

.front {
  transform: rotateX(-12deg) rotateY(45deg) translateZ(150px);
  animation: fade 5s infinite linear -1.25s;
  -webkit-animation: fade 5s infinite linear -1.25s;
}

.back {
  transform: rotateX(168deg) rotateY(-45deg) rotateZ(180deg) translateZ(150px);
  animation: fade 5s infinite linear -3.75s;
  -webkit-animation: fade 5s infinite linear -3.75s;
}

.right {
  transform: rotateX(-12deg) rotateY(135deg) translateZ(150px);
  animation: fade 5s infinite linear;
  -webkit-animation: fade 5s infinite linear;
}

.left {
  transform: rotateX(-12deg) rotateY(-45deg) translateZ(150px);
  animation: fade 5s infinite linear -2.5s;
  -webkit-animation: fade 5s infinite linear -2.5s;
}

.top {
  transform: rotateX(78deg) rotateZ(-45deg) translateZ(150px);
}

.bottom {
  transform: rotateX(-102deg) rotateZ(45deg) translateZ(150px);
}

.front > div {
  background-color: rgba(44,155,222,0.6);
}

.back > div {
  background-color: rgba(43,236,136,0.6);
}

.right > div {
  background-color: rgba(153,242,87,0.6);
}

.left > div {
  background-color: rgba(255,135,58,0.6);
}

.top > div {
  background-color: rgba(239,67,148,0.6);
}

.bottom > div {
  background-color: rgba(115,63,172,0.6);
}

@keyframes fade {
  from { opacity: 1; }
  12.5% { opacity: 0.3; }
  62.5% { opacity: 0.3; }
  75% { opacity: 1; }
}

@-webkit-keyframes fade {
  from { opacity: 1; }
  12.5% { opacity: 0.3; }
  62.5% { opacity: 0.3; }
  75% { opacity: 1; }
}

@keyframes spin {
  from { transform: rotateY(0deg); }
  to { transform: rotateY(-360deg); }
}

@-webkit-keyframes spin {
  from { -webkit-transform: rotateY(0deg); }
  to { -webkit-transform: rotateY(-360deg); }
}

</style>
</head>
<body>
<div class="container">
  <div class="cube">
    <div class="side top"><div></div></div>
    <div class="side front"><div></div></div>
    <div class="side back"><div></div></div>
    <div class="side right"><div></div></div>
    <div class="side left"><div></div></div>
    <div class="side bottom"><div></div></div>
    <div class="questionmark"></div>
  </div>
</div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.17/d3.min.js"></script>
<script>

var user = "tophtucker";

d3.json("https://api.github.com/users/" + user + "/gists",function(err, gists){

gists = gists.filter(function(gist){
    return gist.files && gist.files["index.html"];
  }).map(function(gist){
    return "//bl.ocks.org/" + user + "/raw/" + gist.id;
  });

d3.shuffle(gists);

var sides = d3.selectAll(".side");

sides.append("iframe")
    .attr("marginwidth", 0)
    .attr("marginheight", 0)
    .attr("scrolling", "no");

sides.append("a")
    .attr("class", "hidden")
    .attr("target", "_blank");

sides.transition()
    .delay(function(d,i){
      return i * 2500;
    })
    .each("end", mystery);

function mystery() {

var next = gists[gists.push(gists.shift()) - 1];

var side = d3.select(this),
        iframe = side.select("iframe"),
        link = side.select("a");

link.classed("hidden", false)
      .attr("href", next);

side.select("iframe")
      .on("load",function(){

d3.select(this)
          .transition()
          .duration(100)
          .style("opacity", 1)
          .transition()
            .delay(Math.random() * 7500 + 7500)
            .duration(100)
            .style("opacity", 0)
            .each("end",function(){

link.classed("hidden", true)
                .attr("href", null);

side.transition()
                .delay(3000)
                .each("end", mystery);

});

})
      .attr("src", next);

}

});

</script>
</body>
</html>

https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.17/d3.min.js