.banner {
  background-color: #333;
  padding: 10px 0;
  display: block;
}
.head_logo img {
  margin: 0 auto;
  max-width: 450px;
  width: 90%;
   display:block;
}
@media screen and (max-width:500px) {
  .head_logo img {
    margin: 0 auto;
    max-width: 220px;
    width: 100%;
  }
}