SOURCE

<!-- Yech! Bad PUG!!! :( -->
<div id="wrapper">
  <div class="sub">
    <div class="sub">
      <div class="sub">
        <div class="sub">
          <div class="sub">
            <div class="sub">
              <div class="sub">
                <div class="sub">
                  <div class="sub">
                    <div class="sub">
                      <div class="sub">
                        <div class="sub">
                          <div class="sub">
                            <div class="sub">
                              <div class="sub">
                                <div class="sub">
                                  <div class="sub">
                                    <div class="sub">
                                      <div class="sub">
                                        <div class="sub">
                                          <div class="sub">
                                            <div class="sub">
                                              <div class="sub">
                                                <div class="sub">
                                                  <div class="sub">
                                                    <div class="sub"></div>
                                                  </div>
                                                </div>
                                              </div>
                                            </div>
                                          </div>
                                        </div>
                                      </div>
                                    </div>
                                  </div>
                                </div>
                              </div>
                            </div>
                          </div>
                        </div>
                      </div>
                    </div>
                  </div>
                </div>
              </div>
            </div>
          </div>
        </div>
      </div>
    </div>
  </div>
</div>

#wrapper, .sub {
	background: hsla(200, 50%, 10%, 0.05);
	overflow: hidden;
	box-shadow: 0px 0px 20px 2px hsla(200, 50%, 10%, 0.1) inset;
	border: 1px solid hsla(200, 50%, 10%, 0.1);
}

#wrapper {
	width: 500px;
	height: 500px;
	margin: calc(50vh - 250px) calc(50vw - 250px);
}

.sub {
	position: relative;
	width: 90%;
	height: 90%;
	transform-origin: 50% 50%;
	transform: rotate(12deg);
	animation: 100s rot linear infinite;
}

@keyframes rot {
	0% { transform: rotate(12deg);}
	100% { transform: rotate(372deg);}
}