:root{
  --bg1: #240000;
  --bg2: #7a0000;
  --red: #ff2b2b;
  --gold: #ffd66b;
  --white: #fff7f2;
  --muted: rgba(255,255,255,0.75);
  --glass: rgba(255,255,255,0.08);
  --glass2: rgba(255,255,255,0.12);
  --stroke: rgba(255,255,255,0.16);
  --shadow: rgba(0,0,0,0.3);
}

*{
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body{
  min-height: 100vh;
  font-family: Arial, sans-serif;
  color: var(--white);
  padding: 30px 15px;

  background:
    radial-gradient(circle at top left, rgba(255,214,107,0.22), transparent 35%),
    radial-gradient(circle at top right, rgba(255,43,43,0.22), transparent 35%),
    linear-gradient(135deg, var(--bg1), var(--bg2));
}

main{
  width: 95%;
  max-width: 1200px;
  margin: auto;
  background: rgba(0,0,0,0.2);
  border: 1px solid rgba(255,255,255,0.12);
  border-radius: 24px;
  padding: 30px 25px;
  box-shadow: 0 15px 40px var(--shadow);
  backdrop-filter: blur(8px);
}

h1{
  text-align: center;
  font-size: 32px;
  margin-bottom: 10px;
  color: var(--gold);
}

.sub{
  text-align: center;
  font-size: 16px;
  color: var(--muted);
  margin-bottom: 30px;
}

.menu{
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 18px;
}

.menu a{
  text-decoration: none;
  color: var(--white);
  background: linear-gradient(180deg, var(--glass), var(--glass2));
  border: 1px solid var(--stroke);
  border-radius: 18px;
  min-height: 90px;
  padding: 15px;

  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;

  font-size: 16px;
  font-weight: bold;
  line-height: 1.4;

  box-shadow: 0 8px 20px rgba(0,0,0,0.25);
  transition: all 0.25s ease;
  position: relative;
  overflow: hidden;
}

.menu a::before{
  content: "📁 ";
  font-size: 20px;
  margin-right: 6px;
}

.menu a:hover{
  transform: translateY(-4px) scale(1.02);
  border-color: rgba(255,214,107,0.5);
  background: linear-gradient(180deg, rgba(255,214,107,0.18), rgba(255,255,255,0.10));
  box-shadow: 0 12px 28px rgba(0,0,0,0.35);
}

.menu a:active{
  transform: scale(0.98);
}

.menu a:focus{
  outline: none;
  box-shadow: 0 0 0 4px rgba(255,214,107,0.2);
}

/* Tablet */
@media (max-width: 992px){
  .menu{
    grid-template-columns: repeat(3, 1fr);
  }
}

/* Mobile lớn */
@media (max-width: 768px){
  h1{
    font-size: 28px;
  }

  .sub{
    font-size: 15px;
  }

  .menu{
    grid-template-columns: repeat(2, 1fr);
  }

  .menu a{
    min-height: 80px;
    font-size: 15px;
  }
}

/* Mobile nhỏ */
@media (max-width: 480px){
  main{
    padding: 20px 15px;
  }

  .menu{
    grid-template-columns: 1fr;
  }

  .menu a{
    min-height: 70px;
    font-size: 14px;
  }
}