button  {
    background-color: chartreuse;
    color: cornsilk;
    font-size: 18px;
    padding: 5px;
}

.button {
    padding: 15px 25px;
    font-size: 24px;
    text-align: center;
    cursor: pointer;
    outline: none;
    color: #fff;
    background-color: #04AA6D;
    border: none;
    border-radius: 15px;
    box-shadow: 0 9px #999;
    position: relative;
  }
  
  .button:hover {background-color: #3e8e41}
  
  .button:active {
    background-color: #3e8e41;
    box-shadow: 0 5px #666;
    transform: translateY(4px);
  }
    
    #reference{
    position: fixed;
    bottom: 15px;
    right: 10px;
    }
   #quiz{
       position: fixed;
       bottom: 15px;
       left: 10px;
   }


.activity {
  border-radius: 4px;
  background-color: #f4511e;
  border: none;
  color: #FFFFFF;
  text-align: center;
  font-size: 28px;
  padding: 20px;
  width: 200px;
  transition: all 0.5s;
  cursor: pointer;
  margin: 5px;
}

.activity span {
  cursor: pointer;
  display: inline-block;
  position: relative;
  transition: 0.5s;
}

.activity span:after {
  content: '\00bb';
  position: absolute;
  opacity: 0;
  top: 0;
  right: -20px;
  transition: 0.5s;
}

.activity:hover span {
  padding-right: 25px;
}

.activity:hover span:after {
  opacity: 1;
  right: 0;
}

body{

  margin: 3%;
}