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

:root {
  --bg: #0f1117;
  --surface: #1a1d27;
  --border: #2e3345;
  --text: #e8eaed;
  --muted: #9aa0b0;
  --accent: #6c63ff;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  line-height: 1.6;
  min-height: 100vh;
}

.container {
  max-width: 800px;
  margin: 0 auto;
  padding: 0 1rem;
}

header {
  text-align: center;
  padding: 2.5rem 0 1.5rem;
}

header h1 {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 0.35rem;
}

.subtitle {
  color: var(--muted);
  font-size: 1rem;
}

/* Cards */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1.5rem;
  margin-bottom: 1.25rem;
}

.card h2 {
  font-size: 1.15rem;
  font-weight: 600;
  margin-bottom: 1rem;
}

.card-desc {
  color: var(--muted);
  font-size: 0.9rem;
  margin-top: -0.5rem;
  margin-bottom: 1rem;
}

/* Inputs */
.input-group {
  margin-bottom: 1rem;
}

.input-group label {
  display: block;
  font-size: 0.85rem;
  color: var(--muted);
  margin-bottom: 0.35rem;
}

.input-group input[type="date"] {
  width: 100%;
  padding: 0.6rem 0.75rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text);
  font-size: 1rem;
  font-family: inherit;
}

.input-group input[type="date"]:focus {
  outline: none;
  border-color: var(--accent);
}

.input-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}

@media (max-width: 500px) {
  .input-row {
    grid-template-columns: 1fr;
  }
}

/* Buttons */
.btn-primary {
  display: inline-block;
  padding: 0.65rem 1.5rem;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: 6px;
  font-size: 0.95rem;
  font-family: inherit;
  font-weight: 500;
  cursor: pointer;
  transition: opacity 0.15s;
}

.btn-primary:hover {
  opacity: 0.88;
}

/* Exact Age Display */
.age-display {
  text-align: center;
  margin-bottom: 1.25rem;
}

.age-big {
  font-size: 1.35rem;
  font-weight: 600;
  color: var(--accent);
}

.age-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 0.75rem;
  text-align: center;
}

@media (max-width: 500px) {
  .age-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

.age-unit {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.75rem 0.5rem;
}

.age-unit .unit-val {
  display: block;
  font-size: 1.5rem;
  font-weight: 700;
}

.age-unit .unit-label,
.unit-item .unit-label {
  display: block;
  font-size: 0.75rem;
  color: var(--muted);
  margin-top: 0.15rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

/* Units Section */
.live-counter {
  text-align: center;
  margin-bottom: 1.25rem;
  padding: 1rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
}

.counter-label {
  display: block;
  font-size: 0.8rem;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  margin-bottom: 0.35rem;
}

.counter-val {
  display: block;
  font-size: 2rem;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  color: var(--accent);
}

.units-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.75rem;
}

@media (max-width: 500px) {
  .units-grid {
    grid-template-columns: 1fr 1fr;
  }
}

.unit-item {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.75rem;
  text-align: center;
}

.unit-item .unit-val {
  display: block;
  font-size: 1.25rem;
  font-weight: 700;
}

/* Fun Facts */
.facts-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem;
}

@media (max-width: 500px) {
  .facts-grid {
    grid-template-columns: 1fr;
  }
}

.fact-item {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.75rem;
}

.fact-label {
  display: block;
  font-size: 0.75rem;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  margin-bottom: 0.25rem;
}

.fact-val {
  display: block;
  font-size: 1.1rem;
  font-weight: 600;
}

/* Planets */
.planets-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.75rem;
}

@media (max-width: 600px) {
  .planets-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

.planet-item {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.75rem;
  text-align: center;
}

.planet-name {
  display: block;
  font-size: 0.75rem;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  margin-bottom: 0.2rem;
}

.planet-val {
  display: block;
  font-size: 1.15rem;
  font-weight: 700;
}

/* Inline Result */
.inline-result {
  margin-top: 1rem;
  padding: 1rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  font-size: 1rem;
  font-weight: 500;
}

/* Utility */
.hidden {
  display: none;
}

/* Footer */
footer {
  text-align: center;
  padding: 2rem 0;
  color: var(--muted);
  font-size: 0.85rem;
}