.main_image_{
  margin-bottom: 40px;
}
.thumbnail{
  padding:  5px;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content:center;
}
.thumbnail::before {
  content: "";
  display: block;
  height: 0;
  width: calc((100% - 20px) / 3);
  order: 1;
}
.thumbnail::after {
  content: "";
  display: block;
  height: 0;
  width: calc((100% - 20px) / 3);
}
.thumbnail_image{
  width: calc((100% - 20px) / 3);
}

@media (max-width:768px){
.main_image_{
  margin-bottom: 30px;
}
.thumbnail_image{
  width: calc((100% - 10px) / 2);
}
.thumbnail::before {
  display: none;
}
.thumbnail::after {
  width: calc((100% - 10px) / 2);
}

}