body {
  margin: 0;
  font-family: sans-serif;
  color: #ccc;
  text-align: center;

  /* ⛓️ fondo oscuro serio */
  background: radial-gradient(circle at center, #111111, #000000 70%);
  overflow-x: hidden;
  overflow-y: auto;
}

/* 🌫️ AURA PESADA */
body::before {
  content: "";
  position: absolute;
  top: 40%;
  left: 50%;
  transform: translate(-50%, -50%);

  width: 300px;
  height: 300px;

  background: radial-gradient(circle, rgba(150,150,150,0.15), transparent 70%);
  filter: blur(70px);

  animation: respirarLento 8s infinite ease-in-out;
}

@keyframes respirarLento {
  0% { transform: translate(-50%, -50%) scale(1); }
  50% { transform: translate(-50%, -50%) scale(1.1); }
  100% { transform: translate(-50%, -50%) scale(1); }
}

/* CONTENIDO */
.contenido {
  position: relative;
  z-index: 2;

  max-width: 800px;
  margin: auto;
  padding: 100px 20px 80px;
}

/* ⛓️ SIMBOLO */
.simbolo {
  font-size: 130px;
  color: #aaa;

  animation: peso 3s infinite ease-in-out;

  text-shadow:
    0 0 10px #888,
    0 0 20px #555,
    0 0 40px #333;
}

/* ⛓️ EFECTO PESO */
@keyframes peso {
  0%   { transform: translateY(0); }
  50%  { transform: translateY(8px); }
  100% { transform: translateY(0); }
}

/* TITULO */
h1 {
  font-size: 46px;
  margin: 20px 0;
  color: #ddd;
}

/* TEXTO */
p {
  font-size: 18px;
  line-height: 1.8;
  color: #bbb;
}

/* BOTON */
.volver {
  display: inline-block;
  margin-top: 40px;
  padding: 12px 25px;

  border: 1px solid #888;
  color: #aaa;
  text-decoration: none;

  transition: 0.3s;
}

.volver:hover {
  background: #aaa;
  color: black;
  box-shadow: 0 0 20px #888;
}

/* 📱 RESPONSIVE */
@media (max-width: 768px) {

  .simbolo {
    font-size: 85px;
  }

  h1 {
    font-size: 30px;
  }

  p {
    font-size: 16px;
  }

  .contenido {
    padding: 80px 15px 60px;
  }
}