.center {
  text-align: center;
}
body {
  background-image: url(/modern.jpeg);
  background-size: 100%;
  min-height: 100%;
  background-attachment: fixed;
  overflow: auto;
  background-repeat: no-repeat;
  padding: 20px;
  font-family: sans-serif
}
.nav {
    border: 1px solid #ccc;
    border-width: 1px 0;
    list-style: none;
    margin: 0;
    padding: 0;
    text-align: center; /* « The magic. */
}

.nav li {
    display: inline; /* « More magic. */
}

.nav a {
    display: inline-block; /* « Last bit of magic. */
    padding: 10px;
}
.page {
  background-color: #ffbf80;
  width: 80%;
  margin: auto;
  margin-bottom: 0px;
  padding: 20px;
}
.menu-content {
    max-height: 0;
    overflow: hidden;
    font-family: sans-serif; 
    padding: 0 0 0 50px;
}
.infobox {
}
.infobox label {
  font-family: sans-serif;
  font-size: 30px;
  display: block;
  cursor: pointer;
  background: url(images/infobutton.png);
  background-repeat: no-repeat;
  background-position: left center;
  padding: 10px 0 10px 50px;
}
#menu {
    display: none;
}
header h1 {
  text-align: center;
}
input:checked ~ label {
    background: url(images/infobuttonopen.png);
    background-repeat: no-repeat;
    background-position: left center;
    padding: 10px 0 10px 50px;
}
input:checked ~ .menu-content {
    max-height: 100%;
}