<main>
  <div class="root">
    <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>
    </div>
  </div>
</main>

main {
  display: flex;
  width: 100%;
  height: 100vh;
  justify-content: center;
  align-items: center;
}

div.root {
  position: relative;
  width: 320px;
  height: 320px;
  top: 0;
  left: 0;
}

div {
  --size: 80%;
  box-sizing: border-box;
  position: absolute;
  top: calc((100% - var(--size)) / 2);
  left: calc((100% - var(--size)) / 2);
  width: var(--size);
  height: var(--size);
  border: 1px solid black;
  transform: rotate(15deg);
  animation: rot 1000ms ease 0ms;
}

@keyframes rot {
  from {
    transform: rotate(0);
  }
  to {
    transform: rotate(15deg);
  }
}