.slider {
  overflow: hidden;
  margin:50px auto;
  background:#fff;
}

.track {
  display:flex;
  transition: transform 0.5s ease;
  box-sizing: content-box;
}

.track .slide {
  flex-shrink:0;
  width:180px;
  height:257px;
  margin-right:20px;
}

.track .slide:last-child {
  margin-right:0;
}

.track img {
  width:100%;
  height:100%;
  object-fit:cover;
}

.slider4 { width: 860px; } /* 180*4 + 20*3 */
.track .slide4 {
  flex-shrink:0;
  width:180px;
  height:257px;
  margin-right:20px;
}
.slider4 {
  overflow: hidden;
  margin:50px auto;
  background:#fff;
}

/* PC：5枚表示 */
@media (min-width: 981px) {
  .slider { width: 980px; } /* 180*5 + 20*4 */
}

/* タブレット：4枚表示 */
@media (max-width: 980px) and (min-width: 661px) {
  .slider { width: 740px; } /* 180*4 + 20*3 */
}

/* スマホ：3枚表示 */
@media (max-width: 660px) {
  .slider { width: 340px;   background:#eee6cc;} /* 180*3 + 20*2 */
  .track .slide {
  flex-shrink:0;
  width:160px;
  height:228px;
  margin-right:20px;
}

  
}