:root {
  --bg: #070b14;
  --bg-elevated: #0e1628;
  --bg-card: #121c33;
  --bg-card-hover: #172442;
  --border: rgba(148, 163, 184, 0.16);
  --border-strong: rgba(148, 163, 184, 0.3);

  --text: #f1f5f9;
  --text-muted: #94a3b8;
  --accent: #38bdf8;
  --accent-glow: rgba(56, 189, 248, 0.25);

  --terrestrial: #f59e0b;
  --terrestrial-bg: rgba(245, 158, 11, 0.14);
  --gas: #fb923c;
  --gas-bg: rgba(251, 146, 60, 0.14);
  --ice: #38bdf8;
  --ice-bg: rgba(56, 189, 248, 0.14);
  --dwarf: #c084fc;
  --dwarf-bg: rgba(192, 132, 252, 0.14);
  --moon: #34d399;
  --moon-bg: rgba(52, 211, 153, 0.14);

  --radius: 16px;
  --radius-sm: 10px;
  --shadow: 0 18px 45px rgba(2, 6, 23, 0.55);
  --font-sans: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

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

html {
  scroll-behavior: smooth;
  color-scheme: dark;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  background: radial-gradient(circle at 18% 0%, #111c3a 0%, var(--bg) 52%);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: absolute;
  inset-block-start: -100%;
  inset-inline-start: 1rem;
  z-index: 100;
  padding: 0.65rem 1rem;
  background: var(--accent);
  color: #061224;
  font-weight: 700;
  border-radius: var(--radius-sm);
  text-decoration: none;
}

.skip-link:focus {
  inset-block-start: 1rem;
}

.container {
  width: min(1140px, 100% - 2rem);
  margin-inline: auto;
}

/* Header & Hero */
.site-header {
  position: relative;
  overflow: hidden;
  padding-block: clamp(3.5rem, 8vw, 6.5rem) clamp(3rem, 6vw, 5rem);
  border-bottom: 1px solid var(--border);
}

.starfield {
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    radial-gradient(1.5px 1.5px at 12% 24%, rgba(255, 255, 255, 0.8), transparent),
    radial-gradient(1px 1px at 28% 72%, rgba(255, 255, 255, 0.65), transparent),
    radial-gradient(2px 2px at 44% 18%, rgba(186, 230, 253, 0.85), transparent),
    radial-gradient(1px 1px at 63% 45%, rgba(255, 255, 255, 0.6), transparent),
    radial-gradient(1.5px 1.5px at 78% 22%, rgba(254, 243, 199, 0.85), transparent),
    radial-gradient(1px 1px at 88% 68%, rgba(255, 255, 255, 0.7), transparent),
    radial-gradient(1.5px 1.5px at 35% 88%, rgba(255, 255, 255, 0.55), transparent),
    radial-gradient(1px 1px at 94% 14%, rgba(186, 230, 253, 0.75), transparent);
  opacity: 0.75;
}

.hero {
  position: relative;
  max-width: 760px;
}

.eyebrow {
  margin: 0 0 0.75rem;
  font-size: 0.82rem;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent);
}

h1 {
  margin: 0 0 1rem;
  font-size: clamp(2.1rem, 5vw, 3.4rem);
  line-height: 1.12;
  letter-spacing: -0.02em;
}

.hero-subtitle {
  margin: 0 0 2rem;
  font-size: clamp(1.02rem, 1.8vw, 1.2rem);
  color: var(--text-muted);
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.85rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.78rem 1.35rem;
  border-radius: 999px;
  font-weight: 600;
  font-size: 0.95rem;
  text-decoration: none;
  transition: transform 160ms ease, background-color 160ms ease, border-color 160ms ease;
}

.btn-primary {
  background: var(--accent);
  color: #061224;
  box-shadow: 0 8px 24px var(--accent-glow);
}

.btn-primary:hover {
  background: #7dd3fc;
  transform: translateY(-1px);
}

.btn-secondary {
  background: rgba(148, 163, 184, 0.1);
  color: var(--text);
  border: 1px solid var(--border-strong);
}

.btn-secondary:hover {
  background: rgba(148, 163, 184, 0.18);
  transform: translateY(-1px);
}

/* Sections */
.section {
  padding-block: clamp(2.75rem, 5vw, 4.25rem);
}

.section-header {
  margin-bottom: 1.75rem;
}

.section-header h2 {
  margin: 0 0 0.4rem;
  font-size: clamp(1.55rem, 3vw, 2.05rem);
  letter-spacing: -0.015em;
}

.section-header p {
  margin: 0;
  color: var(--text-muted);
  max-width: 64ch;
}

/* Badges */
.badge {
  display: inline-block;
  padding: 0.25rem 0.65rem;
  border-radius: 999px;
  font-size: 0.74rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.badge-terrestrial {
  color: var(--terrestrial);
  background: var(--terrestrial-bg);
}

.badge-gas {
  color: var(--gas);
  background: var(--gas-bg);
}

.badge-ice {
  color: var(--ice);
  background: var(--ice-bg);
}

.badge-dwarf {
  color: var(--dwarf);
  background: var(--dwarf-bg);
}

.badge-moon {
  color: var(--moon);
  background: var(--moon-bg);
}

/* Taxonomy Grid */
.taxonomy-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.15rem;
}

.tax-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.35rem;
  display: flex;
  flex-direction: column;
  gap: 0.65rem;
}

.tax-card h3 {
  margin: 0.2rem 0 0;
  font-size: 1.18rem;
}

.tax-card p {
  margin: 0;
  color: var(--text-muted);
  font-size: 0.94rem;
}

.tax-members {
  margin-top: auto !important;
  padding-top: 0.65rem;
  border-top: 1px solid var(--border);
  color: var(--text) !important;
  font-size: 0.88rem !important;
}

/* Filter Bar */
.filter-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin-bottom: 1.75rem;
}

.filter-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.55rem 1rem;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: var(--bg-elevated);
  color: var(--text-muted);
  font-family: inherit;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: background-color 150ms ease, color 150ms ease, border-color 150ms ease;
}

.filter-btn:hover {
  color: var(--text);
  border-color: var(--border-strong);
}

.filter-btn.is-active {
  background: var(--accent);
  color: #061224;
  border-color: var(--accent);
}

.filter-btn .count {
  font-size: 0.78rem;
  padding: 0.1rem 0.45rem;
  border-radius: 999px;
  background: rgba(15, 23, 42, 0.35);
}

.filter-btn.is-active .count {
  background: rgba(6, 18, 36, 0.16);
}

/* Planet Cards */
.planet-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 1.15rem;
}

.planet-card {
  position: relative;
  display: flex;
  flex-direction: column;
  text-align: left;
  width: 100%;
  padding: 1.35rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text);
  font-family: inherit;
  cursor: pointer;
  transition: transform 180ms ease, border-color 180ms ease, background-color 180ms ease;
}

.planet-card:hover {
  transform: translateY(-3px);
  background: var(--bg-card-hover);
  border-color: var(--border-strong);
}

.planet-card:focus-visible,
.filter-btn:focus-visible,
.btn:focus-visible,
.dialog-close:focus-visible,
.table-wrapper:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}

.planet-card-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 1rem;
}

/* Pure CSS Planet Spheres */
.planet-orb {
  position: relative;
  width: 58px;
  height: 58px;
  border-radius: 50%;
  flex-shrink: 0;
  box-shadow:
    inset -12px -10px 18px rgba(2, 6, 23, 0.78),
    inset 6px 6px 12px rgba(255, 255, 255, 0.22),
    0 0 22px rgba(56, 189, 248, 0.1);
}

.planet-orb.lg {
  width: 112px;
  height: 112px;
  box-shadow:
    inset -22px -18px 34px rgba(2, 6, 23, 0.8),
    inset 10px 10px 22px rgba(255, 255, 255, 0.25),
    0 0 38px rgba(56, 189, 248, 0.14);
}

.orb-mercury {
  background: radial-gradient(circle at 35% 35%, #cbd5e1, #64748b 65%, #334155);
}

.orb-venus {
  background: radial-gradient(circle at 35% 35%, #fef08a, #d97706 65%, #78350f);
}

.orb-earth {
  background:
    radial-gradient(circle at 58% 42%, rgba(74, 222, 128, 0.85) 0 18%, transparent 20%),
    radial-gradient(circle at 35% 60%, rgba(34, 197, 94, 0.8) 0 14%, transparent 16%),
    radial-gradient(circle at 35% 35%, #60a5fa, #1d4ed8 65%, #1e3a8a);
}

.orb-mars {
  background: radial-gradient(circle at 35% 35%, #fb923c, #c2410c 62%, #7c2d12);
}

.orb-jupiter {
  background: repeating-linear-gradient(
    -12deg,
    #fed7aa 0 10%,
    #d97706 10% 18%,
    #fef3c7 18% 26%,
    #b45309 26% 34%
  );
}

.orb-saturn {
  background: repeating-linear-gradient(
    -8deg,
    #fef08a 0 12%,
    #eab308 12% 22%,
    #fde68a 22% 32%
  );
}

.orb-saturn::after {
  content: "";
  position: absolute;
  inset: 50% -34%;
  height: 36%;
  transform: translateY(-50%) rotate(-18deg);
  border-radius: 50%;
  border: 5px solid rgba(253, 230, 138, 0.72);
  border-top-color: rgba(253, 230, 138, 0.25);
  pointer-events: none;
}

.orb-uranus {
  background: radial-gradient(circle at 35% 35%, #a5f3fc, #22d3ee 62%, #0e7490);
}

.orb-uranus::after {
  content: "";
  position: absolute;
  inset: -18% 44%;
  border-radius: 50%;
  border: 2px solid rgba(165, 243, 252, 0.45);
  transform: rotate(10deg);
  pointer-events: none;
}

.orb-neptune {
  background: radial-gradient(circle at 35% 35%, #60a5fa, #2563eb 62%, #1e3a8a);
}

.orb-ceres {
  background: radial-gradient(circle at 38% 35%, #d6d3d1, #78716c 65%, #44403c);
}

.orb-pluto {
  background: radial-gradient(circle at 35% 35%, #fde68a, #a8a29e 58%, #57534e);
}

.orb-eris {
  background: radial-gradient(circle at 35% 35%, #f8fafc, #94a3b8 65%, #475569);
}

.orb-moon {
  background: radial-gradient(circle at 35% 35%, #e2e8f0, #94a3b8 62%, #475569);
}

.orb-phobos {
  border-radius: 44% 56% 52% 48% / 48% 42% 58% 52%;
  background: radial-gradient(circle at 35% 35%, #a8a29e, #57534e 65%, #292524);
}

.orb-io {
  background:
    radial-gradient(circle at 60% 35%, #dc2626 0 10%, transparent 13%),
    radial-gradient(circle at 32% 62%, #b45309 0 14%, transparent 17%),
    radial-gradient(circle at 35% 35%, #fef08a, #eab308 65%, #a16207);
}

.orb-europa {
  background:
    linear-gradient(28deg, transparent 45%, rgba(180, 83, 9, 0.45) 47%, transparent 49%),
    linear-gradient(-35deg, transparent 58%, rgba(180, 83, 9, 0.38) 60%, transparent 62%),
    radial-gradient(circle at 35% 35%, #f8fafc, #cbd5e1 65%, #94a3b8);
}

.orb-ganymede {
  background: radial-gradient(circle at 35% 35%, #d6d3d1, #78716c 65%, #44403c);
}

.orb-callisto {
  background:
    radial-gradient(circle at 62% 38%, rgba(248, 250, 252, 0.7) 0 4%, transparent 6%),
    radial-gradient(circle at 34% 64%, rgba(226, 232, 240, 0.6) 0 3%, transparent 5%),
    radial-gradient(circle at 48% 28%, rgba(248, 250, 252, 0.55) 0 2.5%, transparent 4%),
    radial-gradient(circle at 35% 35%, #94a3b8, #475569 62%, #1e293b);
}

.orb-titan {
  background: radial-gradient(circle at 35% 35%, #fde047, #f59e0b 60%, #92400e);
  box-shadow:
    inset -12px -10px 18px rgba(2, 6, 23, 0.7),
    0 0 24px rgba(245, 158, 11, 0.28);
}

.orb-enceladus {
  background: radial-gradient(circle at 35% 35%, #ffffff, #e0f2fe 60%, #7dd3fc);
}

.orb-triton {
  background: radial-gradient(circle at 35% 35%, #fbcfe8, #cbd5e1 58%, #64748b);
}

.planet-card h3 {
  margin: 0 0 0.25rem;
  font-size: 1.25rem;
}

.planet-tagline {
  margin: 0 0 1rem;
  color: var(--text-muted);
  font-size: 0.9rem;
}

.planet-meta {
  margin: auto 0 0;
  padding-top: 0.85rem;
  border-top: 1px solid var(--border);
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.5rem 0.75rem;
  font-size: 0.82rem;
}

.planet-meta dt {
  color: var(--text-muted);
}

.planet-meta dd {
  margin: 0;
  font-weight: 600;
}

/* IAU Box */
.iau-box {
  background: linear-gradient(135deg, rgba(56, 189, 248, 0.08), rgba(192, 132, 252, 0.08));
  border: 1px solid var(--border-strong);
  border-radius: var(--radius);
  padding: clamp(1.5rem, 4vw, 2.25rem);
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem 2.25rem;
  align-items: center;
}

.iau-box h2 {
  margin: 0 0 0.6rem;
  font-size: 1.45rem;
}

.iau-box p {
  margin: 0;
  color: var(--text-muted);
}

.iau-list {
  margin: 0;
  padding-inline-start: 1.25rem;
  display: grid;
  gap: 0.75rem;
}

.iau-list li {
  color: var(--text-muted);
  font-size: 0.95rem;
}

.iau-list strong {
  color: var(--text);
}

/* Responsive Comparison Table */
.table-wrapper {
  overflow: auto;
  max-inline-size: 100%;
  max-block-size: min(560px, 78vh);
  container-type: inline-size;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
}

.planet-table {
  width: 100%;
  border-collapse: separate;
  border-spacing: 0;
  text-align: left;
  font-size: 0.92rem;
  --label-2: "Classification";
  --label-3: "Location / Host";
  --label-4: "Diameter (km)";
  --label-5: "Orbital Period";
  --label-6: "Known Moons";
}

.planet-table thead {
  position: sticky;
  inset-block-start: 0;
  z-index: 2;
  background: #16223d;
}

.planet-table th,
.planet-table td {
  padding: 0.85rem 1rem;
  border-bottom: 1px solid var(--border);
  white-space: nowrap;
}

.planet-table thead th {
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
}

.planet-table tbody th {
  position: sticky;
  inset-inline-start: 0;
  z-index: 1;
  background: var(--bg-card);
  font-weight: 700;
}

.planet-table tbody tr:hover td,
.planet-table tbody tr:hover th {
  background: var(--bg-card-hover);
}

.planet-table tbody tr:last-child th,
.planet-table tbody tr:last-child td {
  border-bottom: none;
}

@container (width < 640px) {
  .planet-table,
  .planet-table thead,
  .planet-table tbody,
  .planet-table tr,
  .planet-table th,
  .planet-table td {
    display: block;
  }

  .planet-table thead {
    display: none;
  }

  .planet-table tr {
    margin: 0.85rem;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    overflow: hidden;
    background: var(--bg-elevated);
  }

  .planet-table tbody th {
    position: sticky;
    inset-block-start: 0;
    z-index: 2;
    background: #16223d;
    border-bottom: 1px solid var(--border);
  }

  .planet-table td {
    display: flex;
    justify-content: space-between;
    gap: 1rem;
    white-space: normal;
  }

  .planet-table td:nth-child(2)::before {
    content: var(--label-2) ": ";
    color: var(--text-muted);
    font-weight: 600;
  }

  .planet-table td:nth-child(3)::before {
    content: var(--label-3) ": ";
    color: var(--text-muted);
    font-weight: 600;
  }

  .planet-table td:nth-child(4)::before {
    content: var(--label-4) ": ";
    color: var(--text-muted);
    font-weight: 600;
  }

  .planet-table td:nth-child(5)::before {
    content: var(--label-5) ": ";
    color: var(--text-muted);
    font-weight: 600;
  }

  .planet-table td:nth-child(6)::before {
    content: var(--label-6) ": ";
    color: var(--text-muted);
    font-weight: 600;
  }
}

/* Native Modal Dialog */
.planet-dialog {
  margin: auto;
  padding: 0;
  width: min(680px, 100% - 2rem);
  max-height: 90dvh;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius);
  background: var(--bg-elevated);
  color: var(--text);
  box-shadow: var(--shadow);
}

.planet-dialog:modal {
  overscroll-behavior: contain;
}

.planet-dialog::backdrop {
  background: rgba(2, 6, 23, 0.72);
  backdrop-filter: blur(4px);
  overflow: hidden;
  overscroll-behavior: contain;
}

.dialog-inner {
  padding: clamp(1.25rem, 3vw, 1.85rem);
}

.dialog-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 1.25rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--border);
}

.dialog-title-group h2 {
  margin: 0.45rem 0 0;
  font-size: 1.65rem;
}

.dialog-close {
  width: 38px;
  height: 38px;
  border-radius: 50%;
  border: 1px solid var(--border-strong);
  background: rgba(148, 163, 184, 0.1);
  color: var(--text);
  font-size: 1.4rem;
  line-height: 1;
  cursor: pointer;
}

.dialog-close:hover {
  background: rgba(148, 163, 184, 0.22);
}

.dialog-body {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 1.5rem;
  align-items: start;
}

.dialog-visual {
  padding: 0.75rem 1.25rem;
  display: flex;
  justify-content: center;
}

.dialog-summary {
  margin: 0 0 1.1rem;
  color: var(--text-muted);
}

.dialog-stats {
  margin: 0 0 1.2rem;
  padding: 0.9rem 1rem;
  border-radius: var(--radius-sm);
  background: var(--bg-card);
  border: 1px solid var(--border);
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.75rem 1rem;
}

.dialog-stats dt {
  font-size: 0.78rem;
  color: var(--text-muted);
}

.dialog-stats dd {
  margin: 0;
  font-weight: 600;
  font-size: 0.95rem;
}

.dialog-section + .dialog-section {
  margin-top: 1rem;
}

.dialog-section h3 {
  margin: 0 0 0.25rem;
  font-size: 0.95rem;
  color: var(--accent);
}

.dialog-section p {
  margin: 0;
  color: var(--text-muted);
  font-size: 0.93rem;
}

@media (max-width: 580px) {
  .dialog-body {
    grid-template-columns: 1fr;
  }
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--border);
  padding-block: 2rem;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.88rem;
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .btn,
  .filter-btn,
  .planet-card {
    transition: none;
  }
}