web.css

body {
  font-family: "Helvetica Neue", Helvetica, "Segoe UI", Arial, freesans, sans-serif;
  margin: 1em;
}
#header {
  background-color: #eee;
  margin-bottom: 1em;
  text-align: center;
}
h1 {
  margin: 0;
  line-height: 1.5;
}
#links {
  background-color: #e0e0e0;
  display: table;
  width: 100%;
  height: 1.5em;
}
#links > a {
  display: table-cell;
  vertical-align: middle;
  width: 20%;
  color: #000;
  text-decoration: none;
}
#links > a:hover,
#links > a:focus {
  background-color: #CCC;
  font-weight: bold;
}
a.screenshot {
  display: block;
  width: 640px;
  max-width: 100%;
  margin: auto;
}
a.screenshot > img {
  width: 100%;
}
@media (min-width: 1120px) {
  a.screenshot {
    float: right;
    margin: 0 0 1em 1em;
  }
}
span.hover {
  display: none;
}
a:hover + span.hover {
  display: block;
  position: fixed;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  pointer-events: none;
  background: rgba(0,0,0,0.4);
}
span.hover > img {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  margin: auto;
  width: auto;
  height: auto;
  max-width: 100%;
  max-height: 100%;
  box-shadow: 5px 5px 20px rgba(0,0,0,0.4);
}
@media (max-width: 960px) {
  a.screenshot:hover + span.hover {
    display: none;
  }
}
@supports not (pointer-events: auto) {
  a[href$=".png"] {
    position: relative;
  }
  a[href$=".png"]::after {
    content: " ";
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    z-index: 1;
  }
}
h2 ~ p, h2 ~ p + ul, input + div, div > h3 ~ * {
  margin-left: 1em;
}
input + div {
  margin-top: 1em;
  margin-bottom: 1em;
  margin-left: 1em;
}
h3 {
  display: inline;
}
input:checked + div > h3 ~ * {
  display: none;
}