<div class="button">
  <div class="inner">
    <div class="top"></div>
    <div class="side"></div>
    <div class="bottom"></div>
    
    <div class="menu">
      <div class="lines">
        <div class="line"></div>
        <div class="line"></div>
      </div>
    </div>
    
    <div class="particles">
      <div class="particle"></div>
      <div class="particle"></div>
      <div class="particle"></div>
      <div class="particle"></div>
    </div>
  </div>
</div>

@keyframes floating-menu {
  0% {
    transform: translate3d(-50%, -50%, 0);
  }
  25% {
    transform: translate3d(-50%, -60%, 0);
  }
  75% {
    transform: translate3d(-50%, -40%, 0);
  }
  100% {
    transform: translate3d(-50%, -50%, 0);
  }
}

@keyframes shadow {
  0% {
    transform: rotateX(90deg) translate3d(0, 0, -12px) scale(0.8);
  }
  25% {
    transform: rotateX(90deg) translate3d(0, 0, -12px) scale(0.6);
  }
  75% {
    transform: rotateX(90deg) translate3d(0, 0, -12px) scale(1);
  }
  100% {
    transform: rotateX(90deg) translate3d(0, 0, -12px) scale(0.8);
  }
}

* {
  box-sizing: border-box;
}

body {
  background: #FFAEAE;
}

.button {
  position: absolute;
  top: calc( 50% - 35px );
  left: calc( 50% - 35px );
  width: 74px;
  height: 74px;
   
  border-radius: 50%;
  cursor: pointer;
  perspective: 500px;
  transform: translate3d(0, 0, 0);
  transform-style: preserve-3d;
  
  .inner {
    position: relative;
    width: 100%;
    height: 100%;
    
    perspective: 500px;
    perspective-origin: 50% 500%;
    transition: transform 0.5s cubic-bezier(0.645,  0.045, 0.355, 1.000);
    transform-style: preserve-3d;
  }
  
  .top,
  .bottom {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%; 
      
    bacface-visibility: hidden;
    border-radius: 50%;
  }
  .top {
    background: #ffd364;
    border: 3px solid #8a97ff;
    overflow: hidden;
    transform: translate3d(0, 0, 0);
    z-index: 2;
    
    &:before {
      display: block;
      position: absolute;
      top: -25%;
      left: 0;
      width: 100%;
      height: 25%;

      background: white;
      content: '';
      opacity: 0.5;
      transform: scaleY(1);
      transform-origin: 0 0;
      transition: transform 0.5s cubic-bezier(0.645,  0.045, 0.355, 1.000);
    }
  }
  .bottom {
    background: #fc7a5b;
    border: 3px solid #8a97ff; 
    transform: translate3d(0, 0, -20px);
  }
  
  .side {
    position: absolute;
    top: 50%;
    left: 0;
    width: 100%;
    height: 20px;
    ;
    background: #fc7a5b;
    bacface-visibility: hidden;
    border-color: #8a97ff;
    border-style: solid;
    border-width: 0 3px;
    // opacity: 0.5;
    transform: rotateX(-90deg);
    transform-origin: 50% 0;
    z-index: 1;
  }
  
  .menu {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    
    transition: transform 0.5s cubic-bezier(0.645,  0.045, 0.355, 1.000);
    transform-style: preserve-3d;
    z-index: 2;
    
    &:after {
      display: block;
      position: absolute;
      top: 35px;
      left: 26px;
      width: 22px;
      height: 10px;
      background: black;
      border-radius: 50%;
      content: '';
      opacity: 0;
      transform: rotateX(90deg) translate3d(0, 0, -12px) scale(0.8);
      transition: opacity 0.25s linear 0s;
    }
    
    .lines {
      display: block;
      position: absolute;
      top: 50%;
      left: 50%;
      width: 21px;
      height: 14px;

      transform: translate3d(-50%, -50%, 0);
      z-index: 2;
    }

    .line {
      width: 21px;
      height: 4px;

      background: #8a97ff;
      border-radius: 4px;
      
      &:last-child {
        margin-top: 5px;
      }
    }
  }
 }

@keyframes particle {
  0% {
    bottom: 0;
    opacity: 1;
  }
  
  100% {
    bottom: 50px;
    opacity: 0;
  }
}
.particles {
  position: absolute;
  bottom: 50%;
  left: 0;
  width: 100%;
  height: 100%;	
  
  transform: rotateX(-90deg);
  transform-origin: 50% 100%;
   transform-style: preserve-3d;
  
  .particle {
    position: absolute;
    bottom: 0;
    width: 2px;
    height: 2px;
      
    animation-timing-function: cubic-bezier(0.215,  0.610, 0.355, 1.000);
    animation-iteration-count: infinite;
    background: #8a97ff;
    border-radius: 50%;
    opacity: 0;
    transition: opacity 0.25s linear 0s;
    
 
    &:nth-child(1) {
      left: 20%;
      animation-delay: 0.13s;
      animation-duration: 2s;
      transform: translate3d(0, 0, -10px);
    }
    &:nth-child(2) {
      left: 35%;
      animation-duration: 4s;
      transform: translate3d(0, 0, 15px);
    }
    &:nth-child(3) {
      left: 65%;
      animation-delay: 0.35s;
      animation-duration: 3s;
      transform: translate3d(0, 0, -25px);
    }
    &:nth-child(4) {
      left: 80%;
      animation-delay: 0.29s;
      animation-duration: 2.5s;
      transform: translate3d(0, 0, 5px);
    }
  }
}

.button:hover {
  .inner {
    transform: rotateX(50deg);
  }
  
  .top {
    &:before {
      transform: translate3d(0, 500%, 0) scaleY(1);
    }
  }
  
  .menu {
    transform: translate3d(0, 0, 20px) rotateX(-90deg) scale(1.5);
    
    &:after {
      animation: shadow 3s linear infinite;
      opacity: 0.1;
      transition: opacity 0.25s linear 0.1s;
    }
  
    .lines {
      animation: floating-menu 3s linear infinite;
    }
  }
  
  .particles {
    .particle {
      animation-name: particle;
      opacity: 1;
      transition: opacity 0.25s linear 0.1s;
    }
  }
}