body {
  background: #000 url('https://media.giphy.com/media/3o7aCTfyhYawdOXcFW/giphy.gif') repeat;
  color: lime;
  font-family: "Comic Sans MS", "Courier New", sans-serif;
  text-align: center;
  margin: 0;
  padding: 0;
}

header {
  background: repeating-linear-gradient(45deg, #ff0, #f0f, #0ff, #ff0);
  padding: 10px;
  border-bottom: 5px double #fff;
}

nav a {
  color: #fff;
  background: #f00;
  padding: 5px 10px;
  margin: 0 5px;
  border: 2px inset #000;
  text-decoration: none;
  font-weight: bold;
}

nav a:hover {
  background: #0f0;
  color: #000;
}

#guestbook {
  margin-top: 30px;
  padding: 20px;
  border: 3px dashed lime;
  background: rgba(0,0,0,0.6);
}

#guestEntries {
  list-style: none;
  padding: 0;
}

#guestEntries li {
  background: rgba(255,255,255,0.1);
  margin: 5px 0;
  padding: 5px;
  border: 1px solid lime;
}

.popup {
  position: absolute;
  width: 220px;
  background: #111;
  border: 3px ridge magenta;
  color: lime;
  font-size: 14px;
  padding: 5px;
  cursor: move;
  animation: float 3s ease-in-out infinite alternate;
}

.popup img {
  max-width: 100%;
  display: block;
}

.close-btn {
  display: block;
  background: red;
  color: white;
  text-align: center;
  padding: 2px;
  cursor: pointer;
  font-size: 12px;
}

@keyframes float {
  from { transform: translateY(0px); }
  to { transform: translateY(15px); }
}