#wrap {
  display: flex;
  flex-direction: column;
  justify-content: center;
}

#slider {
  width: 100%;
  margin: 0 auto 20px;
}

.slide-item img {
  width: 100%;
}

#thumbnail-list {
  width: 100%;
  margin: 0 auto;
  display: flex;
  justify-content: space-evenly;
  flex-wrap: wrap;
}

.thumbnail-item {
  flex: 0 1 23%;
  margin-bottom: 30px;
  box-sizing: border-box;
  position: relative;
}
.thumbnail-item:after {
  content: '';
  background-color: rgba(0, 0, 0, 0.5);
  position: absolute;
  display: block;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  opacity: 1;
  transition: .3s opacity linear;
}
.thumbnail-item.thumbnail-current:after {
  opacity: 0;
}
.thumbnail-item img {
  width: 100%;
  margin: 0 auto;
}