/*フェードイン表示設定*/
.box {
  width : 100%; 
  position: absolute;
  top: 40%;
  left: 50%;
  transform: translate(-50%,-50%);
  font-family:"Hiragino Sans", "ヒラギノ角ゴシック";
  font-weight: lighter;
}
.fadein {
    opacity: 0;
    animation: fadein 5s ease forwards;
}
@keyframes fadein {
    100% {  opacity: 1;}
}
 
/*追加延滞時間*/
.off02 {animation-delay: 2s;}
.off03 {animation-delay: 3s;}

.btn {
    display:  inline-block;
    color: #fff;
    text-decoration:  none;
    background-color: #2196F3;
    border-radius: 5px;
    position:  relative;
    height: 50px;
    width: 50px;
    cursor:pointer;
}

.btn::before {
    content:  '';
    width: 20px;
    height: 20px;
    display:  block;
    border-top: solid 2px;
    border-right: solid 2px;
    transform: rotate(135deg);
    position:  absolute;
    top: 0px;
    bottom:  10px;
    left:  0;
    right:  0;
    margin:  auto;
}