body {
  background: #e5e5e5;
  font-family: Helvetica, sans-serif;
  font-size: 1rem;
}
#nav-bar ul {
  list-style-type: none;
  margin: 0;
  padding: 0;
}
.nav-link {
  display: inline;
  float: left;
  color: #23374d;
}
.slides {
  float: left;
  width: 180px;
  height: 180px;
  margin: 10px;
  padding: 20px;
  border: 2px solid magenta;
}
#students {
  clear: both;
}
a {
  text-decoration: none;
  margin: 20px;
  color: #23374d;
  font-size: 1.5rem;
}
h2 {
  text-align: center;
  font-family: Helvetica, sans-serif;
}
.container {
  display: flex;
  height: 130px;
  background: #3c9d9b;
}


@media screen and (max-width: 900px) {
  body {
    background-color: #c0ffb3;
  }
}