html, body {
  height: 100%;
  overflow: hidden;
  background-color: #333; /* o #000, o cualquier tono oscuro */
}

.error-page {
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  height: 100%;
  font-family: Arial, "Helvetica Neue", Helvetica, sans-serif;
}

.error-page h1 {
  font-size: 30vh;
  font-weight: bold;
  position: relative;
  margin: -8vh 0 0;
  padding: 0;
}

.error-page h1::after {
  content: attr(data-h1);
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  color: transparent;
  background: -webkit-repeating-linear-gradient(-45deg, #71b7e6, #69a6ce, #b98acc, #ee8176, #b98acc, #69a6ce, #9b59b6);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-size: 400%;
  text-shadow: 1px 1px 2px rgba(255, 255, 255, 0.25);
  animation: animateTextBackground 10s ease-in-out infinite;
}

.error-page h1 + p {
  color: #d6d6d6;
  font-size: 8vh;
  font-weight: bold;
  line-height: 10vh;
  max-width: 600px;
  position: relative;
}

.error-page h1 + p::after {
  content: attr(data-p);
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  color: transparent;
  text-shadow: 1px 1px 2px rgba(255, 255, 255, 0.5);
  -webkit-background-clip: text;
  -moz-background-clip: text;
  background-clip: text;
}

@keyframes animateTextBackground {
  0% {
    background-position: 0 0;
  }
  25% {
    background-position: 100% 0;
  }
  50% {
    background-position: 100% 100%;
  }
  75% {
    background-position: 0 100%;
  }
  100% {
    background-position: 0 0;
  }
}

@media (max-width: 767px) {
  .error-page h1 {
    font-size: 32vw;
  }

  .error-page h1 + p {
    font-size: 8vw;
    line-height: 10vw;
    max-width: 70vw;
  }
}

.boton-volver {
  position: absolute;
  right: 40px;
  bottom: 40px;
  /*background: linear-gradient(135deg, #71b7e6, #b98acc, #ee8176);*/
  background: #343A40;
  border: none;
  border-radius: 8px;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.2);
  color: white;
  font-size: 18px;
  font-weight: bold;
  padding: 15px 35px;
  text-decoration: none;
  cursor: pointer;
  transition: all 0.3s ease;
  display: block;
  align-items: center;
  gap: 8px;
  font-family: Arial, Helvetica, sans-serif;
}

.boton-volver:hover {
  transform: scale(1.05);
  box-shadow: 0 6px 25px rgba(0, 0, 0, 0.4);
}