<link href="https://fonts.googleapis.com/css?family=Open+Sans:300,400" rel="stylesheet">
<a href="#" class="btn">3D Button</a>

$yellow: #FFE800;
$brown: #404040;
$blue: #1CD3F8;
$angle: 8px;
$angle-o: 4px;

html, body {
  height: 100%;
  font-family: "Open Sans", Arial, Helvetica, sans-serif;
  color: #f2f2f2;
  text-transform: uppercase;
  letter-spacing: 1px;
}

body {
  display: flex;
  justify-content: center;
  align-items: center;
  background-color: $blue;
}

.btn {
  top: 0;
  left: 0;
  transition: all .15s linear 0s;
  position: relative;
  display: inline-block;
  padding: 15px 25px;
  background-color: $yellow;
  
  text-transform: uppercase;
  color: $brown;
  font-family: arial;
  letter-spacing: 1px;
  
  box-shadow: -6px 6px 0 $brown;
  text-decoration: none;
  
  &:hover {
    top: 3px;
    left: -3px;
    box-shadow: -3px 3px 0 $brown;
    
    &::after {
      top: 1px;
      left: -2px;
      width: $angle-o;
      height: $angle-o;
    }
    
    &::before {
      bottom: -2px;
      right: 1px;
      width: $angle-o;
      height: $angle-o;
    }
  }
  
  &::after {
    transition: all .15s linear 0s;
    content: '';
    position: absolute;
    top: 2px;
    left: -4px;
    width: $angle;
    height: $angle;
    background-color: $brown;
    transform: rotate(45deg);
    z-index: -1;
    
  }
  
  &::before {
    transition: all .15s linear 0s;
    content: '';
    position: absolute;
    bottom: -4px;
    right: 2px;
    width: $angle;
    height: $angle;
    background-color: $brown;
    transform: rotate(45deg);
    z-index: -1;
  }
}

a.btn { position: relative; }

a:active.btn {
  top: 6px;
  left: -6px;
  box-shadow: none;
  
  &:before {
    bottom: 1px;
    right: 1px;
  }
  
  &:after {
    top: 1px;
    left: 1px;
  }
}