.concept_inner {
  display: flex;

}

.concept_img {
  max-width: 150px;
  margin-left: 20px;
}

.concept_img_left {
  max-width: 150px;
  margin-right: 20px;
}

.concept_img_left img {
  width: 100%;
}

.concept_img img {
  width: 100%;
}

@media screen and (max-width: 640px) {
  .concept_inner {
  display: block;
}

.concept_img {
  text-align: right;
  max-width: 100%;
}

.concept_img_left {
  text-align: center;
  max-width: 640px;
  margin-right: 0;
  margin-bottom: 10px;
}

.concept_img_left img {
  width: 150px;
}

.concept_img img {
  width: 150px;
}
}