.out{
    position: relative;
}
.in img{
    position: absolute;
    top: 0;
    left: 0;
    opacity: 0;
    transition: .5s;
    z-index: 0;
}
img{
    display: block;
    width: 100%;
    height: auto;
}
input{
    display: none;
}
.in{
    display: flex;
    justify-content: center;
}
label span{
    display: block;
    width: 15px;
    height: 15px;
    padding: 7px;
    margin: -40px 0 0;
    border-radius: 100%;
    cursor: pointer;
    position: relative;
    z-index: 2;
}
label span::before{
    content: "";
    display: block;
    width: 100%;
    height: 100%;
    background: #4287f5;
    opacity: 0.5;
    border-radius: 100%;
}            
input:nth-of-type(1):checked ~ .in label:nth-of-type(1) span::before,
input:nth-of-type(2):checked ~ .in label:nth-of-type(2) span::before,
input:nth-of-type(3):checked ~ .in label:nth-of-type(3) span::before,
input:nth-of-type(4):checked ~ .in label:nth-of-type(4) span::before{
    background: #000;
    opacity: 1;
}
label span::before{
    animation: slidebutton 14s infinite;
}
@keyframes slidebutton{
    0%{opacity: 0.5;background: #4287f5;}
    3.5%{opacity: 1;background: #000;}/* b÷x×100=y */
    25%{opacity: 1;background: #000;}/* 100÷c=z */
    28.5%{opacity: 0.5;background: #4287f5;}/* y+z */
}            
label:nth-of-type(2) span::before,label:nth-of-type(2) img{
    animation-delay: 3.5s;
}            
label:nth-of-type(3) span::before,label:nth-of-type(3) img{
    animation-delay: 7s;
}            
label:nth-of-type(4) span::before,label:nth-of-type(4) img{
    animation-delay: 10.5s;
}            
input:nth-of-type(1):checked ~ .in label:nth-of-type(1) img,
input:nth-of-type(2):checked ~ .in label:nth-of-type(2) img,
input:nth-of-type(3):checked ~ .in label:nth-of-type(3) img,
input:nth-of-type(4):checked ~ .in label:nth-of-type(4) img{
    opacity: 1;
    z-index: 1;
}
.in img{
    animation: slide 14s infinite;/* (a+b)×c=x */
    opacity: 0;
}
@keyframes slide{
    0%{opacity: 0;}
    3.5%{opacity: 1;z-index: 1;}/* b÷x×100=y */
    25%{opacity: 1;}/* 100÷c=z */
    28.5%{opacity: 0;z-index: 0;}/* y+z */
}
input:checked ~ .in img,input:checked ~ .in span::before{
    animation: none;
}
.in:hover img,.in:hover span::before{
    animation-play-state:paused;/* マウスを載せると一時停止 */
}

    @media screen and (max-width: 768px) {
        /* ここにスマホ用のスタイルを入れる */
        .footer-img{
            height: auto;
        }


img{
    /* スマホ画面での長押し禁止 */
    -webkit-touch-callout:none;
    -webkit-user-select:none;
    -moz-touch-callout:none;
    -moz-user-select:none;
    user-select:none;
}