img {
   max-width: 100%;
}

#slider {
   margin: 0 auto;
   width: 800px;
   max-width: 100%;
   text-align: center;
}

#slider label {
   cursor:pointer;
   text-decoration: none;
}

#slides {
   padding: 10px;
   border: 3px solid #ccc;
   background: #fff;
   position: relative;
   z-index: 1;
}

#overflow {
   width: 100%;
   overflow: hidden;
}

#slide1:checked ~ #slides .inner {
   margin-left: 0;
}

#slide2:checked ~ #slides .inner {
   margin-left: -100%;
}

#slide3:checked ~ #slides .inner {
   margin-left: -200%;
}

#slide4:checked ~ #slides .inner {
   margin-left: -300%;
}

#slides .inner {
   transition: margin-left 800ms cubic-bezier(0.770, 0.000, 0.175, 1.000);
   width: 400%;
   line-height: 0;
   height: 300px;
}

#slides .slide {
   width: 25%;
   float:left;
   display: flex;
   justify-content: center;
   align-items: center;
   height: 100%;
   color: #fff;
}

#slides .slide_1 {
   background: #00171F;
}

#slides .slide_2 {
   background: #003459;
}

#slides .slide_3 {
   background: #007EA7;
}

#slides .slide_4 {
   background: #00A8E8;
}

#controls {
   margin: -180px 0 0 0;
   width: 100%;
   height: 50px;
   z-index: 3;
   position: relative;
}

#controls label {
   transition: opacity 0.2s ease-out;
   display: none;
   width: 50px;
   height: 50px;
   opacity: .4;
}

#controls label:hover {
   opacity: 1;
}

#slide1:checked ~ #controls label:nth-child(2),
#slide2:checked ~ #controls label:nth-child(3),
#slide3:checked ~ #controls label:nth-child(4),
#slide4:checked ~ #controls label:nth-child(1) {
   background: url(https://image.flaticon.com/icons/svg/130/130884.svg) no-repeat;
   float:right;
   margin: 0 -50px 0 0;
   display: block;
}

#slide1:checked ~ #controls label:nth-last-child(2),
#slide2:checked ~ #controls label:nth-last-child(3),
#slide3:checked ~ #controls label:nth-last-child(4),
#slide4:checked ~ #controls label:nth-last-child(1) {
   background: url(https://image.flaticon.com/icons/svg/130/130882.svg) no-repeat;
   float:left;
   margin: 0 0 0 -50px;
   display: block;
}

#bullets {
   margin: 150px 0 0;
   text-align: center;
}

#bullets label {
   display: inline-block;
   width: 10px;
   height: 10px;
   border-radius:100%;
   background: #ccc;
   margin: 0 10px;
}

#slide1:checked ~ #bullets label:nth-child(1),
#slide2:checked ~ #bullets label:nth-child(2),
#slide3:checked ~ #bullets label:nth-child(3),
#slide4:checked ~ #bullets label:nth-child(4) {
   background: #444;
}

@media screen and (max-width: 900px) {
   #slide1:checked ~ #controls label:nth-child(2),
   #slide2:checked ~ #controls label:nth-child(3),
   #slide3:checked ~ #controls label:nth-child(4),
   #slide4:checked ~ #controls label:nth-child(1),
   #slide1:checked ~ #controls label:nth-last-child(2),
   #slide2:checked ~ #controls label:nth-last-child(3),
   #slide3:checked ~ #controls label:nth-last-child(4),
   #slide4:checked ~ #controls label:nth-last-child(1) {
      margin: 0;
   }
   #slides {
      max-width: calc(100% - 140px);
      margin: 0 auto;
   }
}