/* Versione B — tema blu. */
html {
  background: #000;
}
body {
  font-family: system-ui, sans-serif;
  margin: 0;
  background: transparent;
  min-height: 100vh;
  color: #fff;
  position: relative;
}
#bg-gradient {
  position: fixed;
  top: 0; left: 0;
  width: 100%; height: 100%;
  background: linear-gradient(to bottom, #004d00, #00008b);
  opacity: 0.55;
  pointer-events: none;
  z-index: 0;
}
header {
  text-align: center;
  padding: 2rem;
}
nav ul {
  list-style: none;
  padding: 0;
  display: flex;
  justify-content: center;
  gap: 1rem;
}
nav a {
  text-decoration: none;
  font-weight: bold;
}
nav a:hover {
  text-decoration: underline;
}
main { 
  max-width: 40rem; 
  margin: 0 auto; 
  padding: 2rem; 
  text-align: center;
}
h1 { font-size: 3rem; margin: 0 0 0.5rem; color: red; }
code { background: rgba(255, 255, 255, .2); padding: .1em .3em; border-radius: .2em; }
a { color: #fff; }

footer {
  color: white;
  text-align: center;
  padding: 0.5rem;
  position: fixed;
  bottom: 0;
  left: 0;
  width: 100%;
}