* {
  box-sizing: border-box;
  font-family: 'Inter', system-ui, sans-serif;
}

body {
  margin: 0;
  background: #0b0d1a;
  color: #f5f5f5;
  overflow-x: hidden;
}

#container {
  width: 100%;
}

/* PANELS */
.panel {
  height: 100vh;
  width: 100%;
  padding: 24px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  text-align: center;
}

/* INTRO */
.intro h1 {
  font-size: 3rem;
  font-weight: 500;
}
.hint {
  opacity: 0.6;
  margin-top: 20px;
}

/* ATMOSPHERE */
.atmosphere {
  background: radial-gradient(circle at top, #1a1f3c, #0b0d1a);
}
.stars {
  position: absolute;
  inset: 0;
  background-image: radial-gradient(#fff 1px, transparent 1px);
  background-size: 22px 22px;
  opacity: 0.15;
}

/* BIRTHDAY */
.birthday {
  background: linear-gradient(180deg, #3a0ca3, #240046);
}
.big-line {
  font-size: 2.5rem;
  margin-bottom: 12px;
}
.sub-line {
  opacity: 0.85;
}

/* CARDS */
.cards {
  background: linear-gradient(135deg, #22223b, #4a4e69);
}
.card-grid {
  display: grid;
  grid-template-columns: repeat(2, 150px);
  gap: 22px;
}
.card {
  height: 150px;
  background: rgba(255,255,255,0.12);
  border-radius: 18px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  backdrop-filter: blur(10px);
  transform-style: preserve-3d;
}
.card span {
  opacity: 0;
  transform: translateY(10px);
}

/* REFLECTION */
.reflection {
  background: #f1faee;
  color: #222;
}
.reflection .line {
  font-size: 1.2rem;
  margin: 8px 0;
}

/* MEANING */
.meaning {
  background: radial-gradient(circle, #0f2027, #203a43);
}

/* LETTER */
.letter {
  background: #f8f5f2;
  color: #222;
}
.paper {
  background: #fff;
  padding: 32px;
  border-radius: 10px;
  max-width: 340px;
  box-shadow: 0 20px 40px rgba(0,0,0,0.15);
}