* {
  box-sizing: border-box;
}

h1, h2 {
  text-align: center;
}

.topo {
  text-align: center;
}

#link-download {
  font-size: 24px;
}

.menu {
  width: 100%;
  display: flex;
  justify-content: center;
}

.menu a:visited {
  color: blue;
}

.menu ul {
  list-style-type: none;
}

.menu li {
  float: left;
  margin-right: 2em;
}

img {
  border: 1px solid #ddd;
  border-radius: 4px;
  padding: 5px;
  width: 256px;
  height: 128px;
}

img:hover {
  box-shadow: 0 0 2px 1px rgba(0, 140, 186, 0.5);
}

dt {
  margin-top: 2em;
  margin-bottom: 1em;
}