body {
  font-family: Arial, sans-serif;
  background-color: #173f2a;
  color: #f5f5f5;
  margin: 0;
  padding: 0;
}
header {
  background-color: #225b3a;
  padding: 1em;
  text-align: center;
  border-bottom: 4px solid #b1d8b7;
}
nav a {
  color: #b1d8b7;
  margin: 0 10px;
  text-decoration: none;
  font-weight: bold;
}
nav a:hover {
  text-decoration: underline;
}
main {
  padding: 2em;
  text-align: center;
}
footer {
  background-color: #225b3a;
  padding: 1em;
  text-align: center;
  position: fixed;
  width: 100%;
  bottom: 0;
}