/* Reset và layout */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  overflow: hidden;
  font-family: 'Segoe UI', sans-serif;
  background: #000;
  color: white;
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
}

.content {
  position: absolute;
  text-align: center;
  z-index: 10;
  padding: 20px;
}

/* Chữ 404 lớn và nổi bật */
h1 {
  font-size: 14rem;              /* ← TO HƠN */
  font-weight: 900;
  margin-bottom: 20px;
  text-shadow: 0 0 25px white;   /* ← PHÁT SÁNG */
  line-height: 1;
}

p {
  font-size: 1.6rem;
  color: #ddd;
}

/* Sao chuyển động */
#stars, #stars2, #stars3 {
  position: absolute;
  width: 100%;
  height: 100%;
  background: transparent;
  display: block;
}

#stars {
  background: url('https://raw.githubusercontent.com/VincentGarreau/particles.js/master/demo/media/starfield.png') repeat;
  animation: moveStars 200s linear infinite;
  z-index: 1;
  opacity: 0.5;
}

#stars2 {
  background: url('https://raw.githubusercontent.com/VincentGarreau/particles.js/master/demo/media/starfield.png') repeat;
  animation: moveStars 400s linear infinite;
  z-index: 2;
  opacity: 0.3;
}

#stars3 {
  background: url('https://raw.githubusercontent.com/VincentGarreau/particles.js/master/demo/media/starfield.png') repeat;
  animation: moveStars 600s linear infinite;
  z-index: 3;
  opacity: 0.2;
}

/* Hiệu ứng chuyển động sao */
@keyframes moveStars {
  from { background-position: 0 0; }
  to   { background-position: -10000px 10000px; }
}




body::before {
  content: "";
  position: absolute;
  top: 0; left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.4); /* lớp mờ */
  z-index: 0;
}
.content {
  position: relative;
  z-index: 1;
}

body {
  margin: 0;
  padding: 0;
  font-family: 'Segoe UI', sans-serif;
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  color: white;
  text-align: center;

  /* Nền là ảnh GIF động bầu trời sao */
  background: url('https://wallpapers-clan.com/wp-content/uploads/2024/03/starfall-night-sky-mountains-aesthetic-gif-preview-desktop-wallpaper.gif') no-repeat center center fixed;
  background-size: cover;
}