body{
  margin: 0;
  padding: 0;
  background-color: #eee;
}
.content-box{
  position: absolute;
  width: 100vw;
  height: 100vh;
  z-index: 9999;
}
.ball-box{
  display: flex;
  padding: 10% 20%;
  flex-wrap: wrap;
  height: auto;
  justify-content: space-around;
}

.ball-box .ball,.ball-box .ball-e{
  text-align: center;
  display: inline-block;
  font-size: 3em;
  width: 2em;
  height: 2em;
  line-height: 200%;
  margin: 0 0.2em;
  font-weight: bold;
  color: #333;
  background-color: #FFF;
  border-radius: 50%;
  box-shadow: 0px 10px 10px RGBA(0, 0, 0, 0.3), inset 0px -10px 30px RGBA(0, 0, 0, 0.6);
  animation: show-number 0.5s ease-out;
  animation-fill-mode: backwards;
  margin-bottom: 20px;
  text-shadow: 2px 2px 4px RGBA(0, 0, 0, 0.2);
  cursor: pointer;
}

.ball-box .space{
  margin-left: 50px;
}



button {
  margin: 20px auto;
}
.custom-btn {
  width: 130px;
  height: 40px;
  color: #fff;
  border-radius: 5px;
  padding: 10px 25px;
  font-family: 'Lato', sans-serif;
  font-weight: 500;
  background: transparent;
  cursor: pointer;
  transition: all 0.3s ease;
  position: relative;
  display: inline-block;
   box-shadow:inset 2px 2px 2px 0px rgba(255,255,255,.5),
   7px 7px 20px 0px rgba(0,0,0,.1),
   4px 4px 5px 0px rgba(0,0,0,.1);
  outline: none;
}


/* 13 */
.btn-13 {
  background-color: #89d8d3;
background-image: linear-gradient(315deg, #89d8d3 0%, #03c8a8 74%);
  border: none;
  z-index: 1;
}
.btn-13:after {
  position: absolute;
  content: "";
  width: 100%;
  height: 0;
  bottom: 0;
  left: 0;
  z-index: -1;
  border-radius: 5px;
   background-color: #4dccc6;
background-image: linear-gradient(315deg, #4dccc6 0%, #96e4df 74%);
  box-shadow:
   -7px -7px 20px 0px #fff9,
   -4px -4px 5px 0px #fff9,
   7px 7px 20px 0px #0002,
   4px 4px 5px 0px #0001;
  transition: all 0.3s ease;
}
.btn-13:hover {
  color: #fff;
}
.btn-13:hover:after {
  top: 0;
  height: 100%;
}
.btn-13:active {
  top: 2px;
}