body {
  background-color: #E6E6E6;
}

header {
  font-family: "Open Sans", Arial, sans-serif;
  text-align: center;
}

header h1 {
  font-size: 4em;
}

header hr {
  border-style: solid;
  border-color: #CCCCCC;
  border-width: 1px 0 0 0;
  margin-bottom: 2em;
  width: 90%;
}

header a {
  font-family: "Arial", "Helvetica", sans-serif;
  font-weight: bold;
  text-decoration: none;
}

header a,
header a:visited {
  color: #AAAAAA;
}

header img {
  height: 1.5ex;
}

main {
   margin: 0 auto;
   width: 800px;
}

.gallery a img {
  height: 192px;
  -webkit-transition: -webkit-transform .15s ease;
  -moz-transition: -moz-transform .15s ease;
  -o-transition: -o-transform .15s ease;
  -ms-transition: -ms-transform .15s ease;
  transition: transform .15s ease;
}

.gallery a:hover img {
  -webkit-transform: scale(1.10);
  -moz-transform: scale(1.10);
  -o-transform: scale(1.10);
  -ms-transform: scale(1.10);
  transform: scale(1.10);
  z-index: 5;
}

@media (max-width: 500px) {
  header h1 {
    font-size: 3em;
  }
}
@media (max-width: 900px) {
  header hr {
    display: none;
  }
  main {
    width: 100%;
  }
  .gallery a img {
    width: 100%;
    height: auto;
  }
}

@media (min-width: 1400px) {
  main {
    width: 1300px;
  }
  .gallery a img {
    height: 300px;
  }
}

@media (min-width: 1900px) {
  main {
    width: 1700px;
  }
}