:root {
  --bg-light: #dee7f3;
  --bg-dark: #1c1c1c;
  --text-light: #2c3e50;
  --text-dark: #f0f0f0;
  --accent: #0066cc;
  --shadow-light: 8px 8px 20px #bec8d4, -8px -8px 20px #ffffff;
  --shadow-dark: 8px 8px 20px #0f0f0f, -8px -8px 20px #2a2a2a;
  --inset-light: inset 6px 6px 12px #bec8d4, inset -6px -6px 12px #ffffff;
  --inset-dark: inset 6px 6px 12px #0f0f0f, inset -6px -6px 12px #2a2a2a;
}

body {
  margin: 0;
  font-family: 'Poppins', sans-serif;
  background: var(--bg-light);
  color: var(--text-light);
  transition: all 0.4s ease;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
}

body.dark {
  background: var(--bg-dark);
  color: var(--text-dark);
}

.card {
  background: var(--bg-light);
  border-radius: 25px;
  box-shadow: var(--shadow-light);
  text-align: center;
  padding: 50px 40px;
  width: 95%;
  max-width: 550px;
  transition: all 0.4s ease;
  animation: pop-in 0.8s ease;
}

body.dark .card {
  background: var(--bg-dark);
  box-shadow: var(--shadow-dark);
}

@keyframes pop-in {
  from { transform: scale(0.9); opacity: 0; }
  to { transform: scale(1); opacity: 1; }
}

h1 {
  font-size: 2.8rem;
  margin-bottom: 10px;
}

h2 {
  font-size: 1.6rem;
  color: var(--accent);
  margin-bottom: 30px;
}

.toggle-btn {
  margin-bottom: 25px;
  padding: 10px 20px;
  font-size: 1rem;
  border: none;
  border-radius: 15px;
  background: var(--bg-light);
  box-shadow: var(--shadow-light);
  cursor: pointer;
  transition: all 0.3s ease;
}

body.dark .toggle-btn {
  background: var(--bg-dark);
  box-shadow: var(--shadow-dark);
  color: var(--text-dark);
}

.countdown {
  font-size: 1.3rem;
  padding: 18px 22px;
  border-radius: 15px;
  background: var(--bg-light);
  box-shadow: var(--inset-light);
  color: inherit;
  font-weight: 600;
  margin-bottom: 25px;
  transition: all 0.3s ease;
}

body.dark .countdown {
  background: var(--bg-dark);
  box-shadow: var(--inset-dark);
}

p {
  font-size: 1rem;
  line-height: 1.6;
}

.credits {
  margin-top: 30px;
  padding: 18px;
  background: var(--bg-light);
  border-radius: 15px;
  box-shadow: var(--inset-light);
  font-size: 0.95rem;
  transition: all 0.3s ease;
}

body.dark .credits {
  background: var(--bg-dark);
  box-shadow: var(--inset-dark);
}

.credits strong {
  display: block;
  margin-top: 5px;
  color: var(--accent);
}