style.css

* {
  box-sizing: border-box;
}

body {
  background-color: #fef9f2;
  display: flex;
  align-items: center;
  justify-content: space-around;
  height: 100vh;
  overflow: hidden;
  margin: 0;
}

/* spinner */

.spinner {
  width: 100px;
  height: 100px;
  position: relative;
}

.spinner div {
  position: absolute;
  width: 100%;
  height: 100%;
  border: 10px solid transparent;
  border-top-color: #ad60f5;
  border-radius: 50%;
  animation: spinnerOne 1.2s linear infinite;
}

.spinner div:nth-child(2) {
  border: 10px solid transparent;
  border-bottom-color: #ad60f5;
  animation: spinnerTwo 1.2s linear infinite;
}

@keyframes spinnerOne {
  0% {
    transform: rotate(0deg);
    border-width: 10px;
  }
  50% {
    transform: rotate(180deg);
    border-width: 1px;
  }
  100% {
    transform: rotate(360deg);
    border-width: 10px;
  }
}

@keyframes spinnerTwo {
  0% {
    transform: rotate(0deg);
    border-width: 1px;
  }
  50% {
    transform: rotate(180deg);
    border-width: 10px;
  }
  100% {
    transform: rotate(360deg);
    border-width: 1px;
  }
}

/* bouncing balls */

.bouncer {
  display: flex;
  justify-content: space-around;
  align-items: flex-end;
  width: 100px;
  height: 100px;
}

.bouncer div {
  width: 20px;
  height: 20px;
  background-color: #0077ff;
  border-radius: 50%;
  animation: bouncer 0.5s cubic-bezier(0.19, 0.57, 0.3, 0.98) infinite alternate;
  /* use https://cubic-bezier.com/ to customize the curve */
}

.bouncer div:nth-child(2) {
  animation-delay: 0.1s;
  opacity: 0.8;
}

.bouncer div:nth-child(3) {
  animation-delay: 0.2s;
  opacity: 0.6;
}

.bouncer div:nth-child(4) {
  animation-delay: 0.3s;
  opacity: 0.4;
}

@keyframes bouncer {
  from {
    transform: translateY(0);
  }
  to {
    transform: translateY(-100px);
  }
}

/* flipping squares */

.square {
  width: 100px;
  height: 100px;
  position: relative;
  perspective: 200px;
}

.square div {
  position: absolute;
  top: 0;
  height: 50px;
  width: 50px;
  background: coral;
  animation: flip 2s linear infinite;
  transform-origin: right bottom;
}

.square div:nth-child(2) {
  animation-delay: 1s;
  opacity: 0.5;
}

@keyframes flip {
  0% {
    transform: rotateX(0) rotateY(0);
  }
  25% {
    transform: rotateX(0) rotateY(180deg);
  }
  50% {
    transform: rotateX(180deg) rotateY(180deg);
  }
  75% {
    transform: rotateX(180deg) rotateY(0);
  }
  100% {
    transform: rotateX(0) rotateY(0);
  }
}