.header-banner{
  max-width: 1800px;
  margin: auto;
  height: 500px;
  padding-top: 350px;
  background: linear-gradient( rgba(0, 0, 0, 0), rgba(3, 60, 122, 0), rgba(0, 0, 0, 0.583)), url(../images/Gallery\ banner.jpg);
  background-position: center;
  background-size: 100% 120%;
  text-align: center;
  color: white;
  /* margin-top: -120px; */
}

.Gallery-img{
  max-width: 1800px;
  margin: auto;
  padding: 20px;
  display: flex;
  flex-wrap: wrap;
  justify-content: space-evenly;
  margin-top: 30px;
}
.Gallery-img img{
  width: 23%;
  margin: 10px;
  margin-top: 20px;
  height: 450px;
}

  @media screen and (max-width: 900px) {

    .header-banner{
      background-size: 150% 100%;
      height: 300px;
      padding-top: 200px;
      /* margin-top: -120px; */
    }

    .Gallery-img img{
      width: 100%;
      margin: 10px;
      margin-top: 20px;
      height: 400px;
    }

}