pre {
  border: 1px solid black;
  border-width: 1px 2px;
  width: 632px;
  min-height: 352px;
  margin: auto;
}
a {
  color: #5555FF;
  text-decoration: none;
}
a:hover {
  background: #5555ff;
  color: #ffffff;
}
.color1 {
  color: #FF55FF;
}
.color2 {
  color: #FF5555;
}
.color3 {
  color: #0000AA;
}
a.headerlink {
  color: #c60f0f;
  font-size: 0.6em;
  padding: 0 4px 0 4px;
  text-decoration: none;
}
a.headerlink:hover {
  background-color: #c60f0f;
  color: white;
}
a.headerlink {
  visibility: hidden;
}
h1 {
  text-align: center;
}
h1:hover > a.headerlink {
    visibility: visible;
}