body {
  font-family: 'Segoe UI', sans-serif;
  background-color: #0d1117;
  color: #ffffff;
  margin: 0;
  padding: 0;
}
header, footer {
  background: #161b22;
  text-align: center;
  padding: 20px;
}
nav a {
  color: #58a6ff;
  margin: 0 10px;
  text-decoration: none;
}
main {
  padding: 40px;
  text-align: center;
}
img {
  border-radius: 15px;
  box-shadow: 0 0 20px rgba(0,0,0,0.5);
}