html, body{
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
h3 {
  margin: 30px auto;
  text-align: center;
  line-height: 1;
  color: #888;
  font-size: 16px;
  font-weight: bold;
  font-family: sans-serif;
}
.nk_tiles {
  --cols: 3;
  display: flex;
  flex-direction: column;
  flex-wrap: wrap;
  max-width: 1070px;
  width: 100%;
  margin: 30px auto;
}
.nk_tiles .item {
  position: relative;
  width: 33.333334%;
  background-repeat: no-repeat;
  background-position: center;
  background-size: cover;
  transition: all 0.3s;
  /*cursor: pointer;*/
}
.nk_tiles .item:hover {
  opacity: 0.8;
}
@media screen and (max-width: 720px) {
  .nk_tiles {
    --cols: 2;
  }
  .nk_tiles .item {
    width: 50%;
  }
}
@media screen and (max-width: 520px) {
  .nk_tiles {
    --cols: 1;
  }
  .nk_tiles .item {
    width: 100%;
  }
}