:root {
  color-scheme: dark;
  --bg: #07111f;
  --bg-soft: #0d1a30;
  --panel: rgba(11, 20, 37, 0.72);
  --panel-strong: rgba(16, 29, 53, 0.88);
  --border: rgba(135, 180, 255, 0.16);
  --border-strong: rgba(255, 202, 112, 0.34);
  --text: #f5f1e8;
  --muted: #a2b6ca;
  --gold: #ffb74a;
  --gold-soft: #ffd77f;
  --blue: #66b6ff;
  --blue-soft: #98dcff;
  --red: #d96f47;
  --shadow: 0 30px 80px rgba(0, 0, 0, 0.36);
  --radius: 26px;
  --max-width: 1200px;
  --reveal-duration: 0.8s;
  --transition-smooth: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

* { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  color: var(--text);
  font: 16px/1.65 "Outfit", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  background:
    radial-gradient(circle at 18% 18%, rgba(255, 179, 71, 0.16), transparent 20%),
    radial-gradient(circle at 82% 16%, rgba(102, 182, 255, 0.16), transparent 22%),
    radial-gradient(circle at 50% 110%, rgba(21, 56, 117, 0.9), transparent 42%),
    linear-gradient(180deg, #07101d 0%, #091321 35%, #0c1830 100%);
  overflow-x: hidden;
}

/* ========== Starlit background ========== */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  background-image:
    radial-gradient(circle at 10% 30%, rgba(255,255,255,0.9) 0 1px, transparent 1.5px),
    radial-gradient(circle at 25% 80%, rgba(255,255,255,0.8) 0 1px, transparent 1.5px),
    radial-gradient(circle at 70% 20%, rgba(255,255,255,0.85) 0 1px, transparent 1.5px),
    radial-gradient(circle at 85% 65%, rgba(255,255,255,0.7) 0 1px, transparent 1.5px),
    radial-gradient(circle at 58% 42%, rgba(255,255,255,0.75) 0 1px, transparent 1.5px);
  background-size: 280px 280px, 340px 340px, 360px 360px, 420px 420px, 500px 500px;
  pointer-events: none;
  opacity: 0.45;
}

/* ========== Twinkling star field ========== */
.star-field {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 0;
  background-image:
    radial-gradient(1px 1px at 5% 12%, rgba(255,255,255,0.7), transparent),
    radial-gradient(1px 1px at 15% 48%, rgba(255,255,255,0.5), transparent),
    radial-gradient(1.5px 1.5px at 22% 78%, rgba(255,255,255,0.8), transparent),
    radial-gradient(1px 1px at 35% 8%, rgba(255,255,255,0.6), transparent),
    radial-gradient(1.5px 1.5px at 42% 55%, rgba(255,255,255,0.9), transparent),
    radial-gradient(1px 1px at 55% 32%, rgba(255,255,255,0.5), transparent),
    radial-gradient(1.5px 1.5px at 68% 90%, rgba(255,255,255,0.7), transparent),
    radial-gradient(1px 1px at 76% 42%, rgba(255,255,255,0.8), transparent),
    radial-gradient(1.5px 1.5px at 88% 16%, rgba(255,255,255,0.6), transparent),
    radial-gradient(1px 1px at 92% 72%, rgba(255,255,255,0.5), transparent),
    radial-gradient(1px 1px at 3% 92%, rgba(255,255,255,0.7), transparent),
    radial-gradient(1.5px 1.5px at 48% 2%, rgba(255,255,255,0.8), transparent),
    radial-gradient(1px 1px at 62% 66%, rgba(255,255,255,0.5), transparent),
    radial-gradient(1.5px 1.5px at 79% 80%, rgba(255,255,255,0.9), transparent),
    radial-gradient(1px 1px at 95% 38%, rgba(255,255,255,0.6), transparent);
  animation: twinkle 4s ease-in-out infinite alternate;
}

@keyframes twinkle {
  0% { opacity: 0.3; }
  50% { opacity: 0.7; }
  100% { opacity: 0.4; }
}

/* ========== Scroll progress bar ========== */
.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  width: 0%;
  height: 3px;
  background: linear-gradient(90deg, var(--gold-soft), var(--gold), #ff8a2e);
  z-index: 1000;
  transition: width 50ms linear;
  box-shadow: 0 0 12px rgba(255, 183, 74, 0.4);
}

/* ========== Sky layers ========== */
.sky-layer {
  position: fixed;
  inset: -10%;
  pointer-events: none;
  filter: blur(90px);
}

.sky-layer-a {
  background:
    radial-gradient(circle at 20% 20%, rgba(255, 184, 90, 0.24), transparent 18%),
    radial-gradient(circle at 80% 40%, rgba(91, 145, 255, 0.22), transparent 22%);
}

.sky-layer-b {
  background:
    radial-gradient(circle at 45% 65%, rgba(11, 84, 184, 0.22), transparent 24%),
    radial-gradient(circle at 72% 72%, rgba(255, 132, 89, 0.12), transparent 16%);
  transform: translateY(40px);
}

/* ========== Z-index layers ========== */
.site-header,
.section,
.site-footer,
.hero {
  position: relative;
  z-index: 1;
}

/* ========== Header ========== */
.site-header {
  width: min(var(--max-width), calc(100% - 32px));
  margin: 18px auto 0;
  padding: 14px 18px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  border: 1px solid rgba(255,255,255,0.08);
  border-radius: 999px;
  background: rgba(8, 14, 28, 0.58);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  position: sticky;
  top: 16px;
}

.brand,
.site-nav a,
.button,
.planet-card {
  text-decoration: none;
}

.brand {
  color: var(--text);
  font-family: "Noto Serif SC", serif;
  font-size: 1.1rem;
  letter-spacing: 0.08em;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 18px;
  flex-wrap: wrap;
}

.site-nav a {
  color: var(--muted);
  font-size: 0.95rem;
  transition: color 180ms ease;
  position: relative;
}

.site-nav a::after {
  content: "";
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--gold-soft);
  border-radius: 2px;
  transition: width var(--transition-smooth);
}

.site-nav a:hover::after,
.site-nav a.is-active::after {
  width: 100%;
}

.site-nav a:hover,
.site-nav a.is-active {
  color: var(--gold-soft);
}

/* ========== Main layout ========== */
main {
  width: min(var(--max-width), calc(100% - 32px));
  margin: 0 auto;
}

/* ========== Hero ========== */
.hero {
  position: relative;
  display: grid;
  grid-template-columns: 1fr;
  align-items: start;
  min-height: calc(100vh - 120px);
  padding: 60px 0 40px;
  overflow: visible;
}

.eyebrow {
  margin: 0 0 14px;
  color: var(--gold-soft);
  font-size: 0.82rem;
  letter-spacing: 0.24em;
  text-transform: uppercase;
}

h1, h2, h3 {
  margin: 0;
  font-family: "Noto Serif SC", serif;
  font-weight: 700;
}

h1 {
  font-size: clamp(1.6rem, 3vw, 2.4rem);
  line-height: 1.3;
  max-width: 16ch;
}

h2 {
  font-size: clamp(1.8rem, 3vw, 3rem);
  line-height: 1.18;
  max-width: 16ch;
}

h3 {
  font-size: 1.35rem;
  line-height: 1.3;
}

.hero-text,
.panel p,
.site-footer p {
  color: var(--muted);
}

.hero-text {
  max-width: 58ch;
  margin: 18px 0 0;
  font-size: 1rem;
}

.hero-copy {
  position: relative;
  z-index: 2;
  max-width: 480px;
  padding-right: 24px;
}

.hero-actions {
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
  margin-top: 30px;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 0 20px;
  border-radius: 999px;
  font-weight: 600;
  transition: transform 180ms ease, border-color 180ms ease, background 180ms ease, box-shadow 180ms ease;
  cursor: pointer;
}

.button:hover {
  transform: translateY(-3px);
}

.button-primary {
  color: #102036;
  background: linear-gradient(135deg, var(--gold-soft), var(--gold));
  box-shadow: 0 12px 34px rgba(255, 183, 74, 0.22);
}

.button-primary:hover {
  box-shadow: 0 18px 42px rgba(255, 183, 74, 0.35);
}

.button-secondary {
  color: var(--text);
  border: 1px solid rgba(255,255,255,0.12);
  background: rgba(255,255,255,0.03);
}

.button-secondary:hover {
  border-color: rgba(255,255,255,0.25);
  background: rgba(255,255,255,0.06);
}

/* ========== Hero stats ========== */
.hero-stats {
  list-style: none;
  display: flex;
  gap: 16px;
  padding: 0;
  margin: 38px 0 0;
  flex-wrap: wrap;
}

.hero-stats li,
.panel {
  border: 1px solid var(--border);
  background: linear-gradient(180deg, rgba(255,255,255,0.05), rgba(255,255,255,0.015)), var(--panel);
  box-shadow: var(--shadow);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
}

.hero-stats li {
  min-width: 150px;
  padding: 16px 18px;
  border-radius: 20px;
  transition: transform var(--transition-smooth), border-color var(--transition-smooth);
}

.hero-stats li:hover {
  transform: translateY(-2px);
  border-color: rgba(255, 214, 134, 0.24);
}

.hero-stats strong {
  display: block;
  font-size: 1.8rem;
  color: var(--text);
}

.hero-stats span {
  color: var(--muted);
  font-size: 0.92rem;
}

/* ========== Hero Orbit / Viewer ========== */
.hero-orbit {
  position: absolute;
  right: 0;
  top: 0;
  width: 50vw;
  height: 100%;
  z-index: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 16px;
}



/* ========== Animated Solar System ========== */
.solar-system {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  height: 70vh;
  min-height: 500px;
  align-self: center;
}

/* Sun */
.ss-sun {
  position: relative;
  width: 120px;
  height: 120px;
  z-index: 10;
}

.ss-sun-core {
  position: absolute;
  inset: 0;
  border-radius: 50%;
  background: radial-gradient(circle at 35% 30%, #ffeeaa, #ffb74a 50%, #ff8a2e 80%);
  box-shadow:
    0 0 80px rgba(255, 183, 74, 0.5),
    0 0 160px rgba(255, 183, 74, 0.25),
    0 0 240px rgba(255, 183, 74, 0.1);
  animation: sun-pulse 3s ease-in-out infinite;
}

.ss-sun-glow {
  position: absolute;
  inset: -80px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(255, 183, 74, 0.12), transparent 60%);
  animation: sun-glow-pulse 4s ease-in-out infinite;
}

@keyframes sun-pulse {
  0%, 100% { transform: scale(1); box-shadow: 0 0 80px rgba(255, 183, 74, 0.5), 0 0 160px rgba(255, 183, 74, 0.25); }
  50% { transform: scale(1.04); box-shadow: 0 0 100px rgba(255, 183, 74, 0.6), 0 0 200px rgba(255, 183, 74, 0.3); }
}

@keyframes sun-glow-pulse {
  0%, 100% { opacity: 0.6; transform: scale(1); }
  50% { opacity: 1; transform: scale(1.08); }
}

/* Orbits */
.ss-orbit {
  position: absolute;
  width: var(--orbit-size);
  height: var(--orbit-size);
  top: 50%;
  left: 50%;
  margin-left: calc(var(--orbit-size) / -2);
  margin-top: calc(var(--orbit-size) / -2);
  border: 1px solid rgba(135, 180, 255, 0.12);
  border-radius: 50%;
  animation: ss-spin var(--orbit-speed) linear infinite;
  will-change: transform;
  pointer-events: none;
}

/* Planets */
.ss-planet {
  position: absolute;
  top: -3px;
  left: 50%;
  margin-left: calc(var(--planet-size) / -2);
  width: var(--planet-size);
  height: var(--planet-size);
  border-radius: 50%;
  background: var(--planet-color);
  box-shadow:
    0 0 8px var(--planet-color),
    0 0 16px color-mix(in srgb, var(--planet-color) 30%, transparent);
  will-change: transform;
}

/* Saturn ring */
.ss-planet-ringed::after {
  content: "";
  position: absolute;
  top: 50%;
  left: 50%;
  width: 200%;
  height: 4px;
  margin-top: -2px;
  margin-left: -100%;
  border-radius: 50%;
  border: 2px solid rgba(206, 180, 136, 0.6);
  background: transparent;
  transform: rotate(-15deg);
}

/* Labels */
.ss-labels {
  position: absolute;
  inset: 0;
  pointer-events: none;
}

.ss-label {
  position: absolute;
  font-size: 0.6rem;
  color: rgba(255, 255, 255, 0.35);
  letter-spacing: 0.08em;
  white-space: nowrap;
  font-weight: 500;
  text-shadow: 0 0 8px rgba(0,0,0,0.8);
}

@keyframes ss-spin {
  from { transform: rotate(0deg); }
  to { transform: rotate(360deg); }
}

/* ========== Viewer HUD ========== */

/* ========== Viewer Controls ========== */
.viewer-controls {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  padding: 14px;
  border: 1px solid rgba(255,255,255,0.08);
  border-radius: 24px;
  background:
    linear-gradient(180deg, rgba(255,255,255,0.08), rgba(255,255,255,0.02)),
    rgba(8, 14, 28, 0.38);
  box-shadow:
    inset 0 1px 0 rgba(255,255,255,0.08),
    0 12px 30px rgba(0, 0, 0, 0.18);
  backdrop-filter: blur(20px) saturate(145%);
  -webkit-backdrop-filter: blur(20px) saturate(145%);
}

.viewer-button {
  min-height: 40px;
  padding: 0 14px;
  border: 1px solid rgba(255,255,255,0.1);
  border-radius: 999px;
  color: var(--muted);
  background: rgba(255,255,255,0.03);
  font: inherit;
  text-decoration: none;
  cursor: pointer;
  transition: border-color 180ms ease, color 180ms ease, transform 180ms ease, background 180ms ease;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

.viewer-button:hover,
.viewer-button.is-active {
  color: var(--text);
  border-color: rgba(255, 210, 124, 0.34);
  background: rgba(255, 210, 124, 0.08);
  transform: translateY(-1px);
}

/* ========== Planet chip visuals ========== */
.orbit-body,
.planet-chip,
.planet-visual {
  --planet-base: radial-gradient(circle at 35% 30%, #ddd, #666 75%);
  --planet-texture: linear-gradient(90deg, rgba(255,255,255,0.1), rgba(0,0,0,0.1));
  --planet-day: 18s;
  --planet-glow: rgba(255,255,255,0.08);
  --planet-shadow: rgba(0, 0, 0, 0.46);
  position: relative;
  display: inline-grid;
  place-items: center;
  border-radius: 50%;
}

.orbit-body {
  width: var(--size);
  height: var(--size);
  margin-top: calc(var(--size) * -0.48);
}

.planet-surface {
  position: absolute;
  inset: 0;
  border-radius: 50%;
  overflow: hidden;
  background: var(--planet-base);
  box-shadow:
    inset -12px -16px 24px var(--planet-shadow),
    inset 10px 10px 16px rgba(255,255,255,0.12),
    0 0 20px var(--planet-glow);
}

.planet-surface::before {
  content: "";
  position: absolute;
  inset: -8% -45%;
  background: var(--planet-texture);
  background-size: 200% 100%;
}

.planet-surface::after {
  content: "";
  position: absolute;
  inset: 0;
  background:
    radial-gradient(circle at 34% 28%, rgba(255,255,255,0.34), transparent 24%),
    linear-gradient(90deg, rgba(255,255,255,0.02) 0%, rgba(255,255,255,0.03) 38%, rgba(0,0,0,0.18) 60%, rgba(0,0,0,0.54) 100%);
}

.planet-ring {
  position: absolute;
  inset: 50% -26% auto;
  height: 22%;
  border-radius: 50%;
  border: 3px solid rgba(225, 203, 150, 0.82);
  transform: translateY(-50%) rotate(-18deg);
  box-shadow: 0 0 12px rgba(233, 212, 170, 0.18);
}

/* ========== Planet color definitions ========== */
.mercury { --size: 12px; --planet-day: 5.5s; --planet-glow: rgba(207, 184, 153, 0.12); --planet-base: radial-gradient(circle at 30% 28%, #d8d0c1 0%, #aa9e8c 36%, #75695c 72%, #4d463d 100%); --planet-texture: repeating-linear-gradient(104deg, rgba(251, 243, 232, 0.16) 0 5px, rgba(120, 106, 93, 0.22) 5px 12px, rgba(74, 63, 53, 0.24) 12px 18px); }
.venus { --size: 17px; --planet-day: 7s; --planet-glow: rgba(229, 178, 116, 0.14); --planet-base: radial-gradient(circle at 32% 28%, #f1d8ab 0%, #d7a26e 42%, #9f6a42 72%, #684327 100%); --planet-texture: repeating-linear-gradient(90deg, rgba(255, 234, 197, 0.18) 0 7px, rgba(192, 126, 84, 0.24) 7px 15px, rgba(126, 79, 44, 0.24) 15px 22px); }
.earth { --size: 18px; --planet-day: 6.5s; --planet-glow: rgba(118, 174, 255, 0.16); --planet-base: radial-gradient(circle at 34% 28%, #9de0ff 0%, #2f7bf6 44%, #184b9d 74%, #0a1f4b 100%); --planet-texture: repeating-linear-gradient(90deg, rgba(52, 144, 255, 0.18) 0 9px, rgba(34, 96, 181, 0.18) 9px 15px, rgba(124, 215, 165, 0.42) 15px 22px, rgba(17, 92, 45, 0.22) 22px 28px, rgba(43, 115, 201, 0.18) 28px 36px); }
.mars { --size: 14px; --planet-day: 8s; --planet-glow: rgba(214, 111, 71, 0.14); --planet-base: radial-gradient(circle at 32% 28%, #efb07a 0%, #cb6d42 44%, #923d24 74%, #5e2416 100%); --planet-texture: repeating-linear-gradient(92deg, rgba(244, 184, 120, 0.16) 0 6px, rgba(170, 78, 43, 0.24) 6px 13px, rgba(102, 43, 26, 0.24) 13px 19px); }
.jupiter { --size: 33px; --planet-day: 10s; --planet-glow: rgba(212, 164, 114, 0.12); --planet-base: radial-gradient(circle at 32% 28%, #f0dec0 0%, #d0aa7e 42%, #9c7151 70%, #6d4832 100%); --planet-texture: repeating-linear-gradient(90deg, rgba(255, 235, 207, 0.18) 0 8px, rgba(193, 145, 105, 0.28) 8px 16px, rgba(158, 107, 70, 0.24) 16px 24px, rgba(232, 201, 160, 0.16) 24px 29px, rgba(120, 80, 54, 0.22) 29px 36px); }
.saturn { --size: 28px; --planet-day: 10.5s; --planet-glow: rgba(223, 204, 152, 0.12); --planet-base: radial-gradient(circle at 32% 28%, #f1e1bf 0%, #ceb488 42%, #9e8158 72%, #6b5336 100%); --planet-texture: repeating-linear-gradient(90deg, rgba(246, 230, 194, 0.18) 0 8px, rgba(196, 164, 115, 0.26) 8px 14px, rgba(132, 102, 67, 0.22) 14px 21px); }
.uranus { --size: 22px; --planet-day: 9s; --planet-glow: rgba(167, 234, 255, 0.14); --planet-base: radial-gradient(circle at 32% 28%, #dff8ff 0%, #8ed6e8 46%, #4f99bf 72%, #295d82 100%); --planet-texture: repeating-linear-gradient(90deg, rgba(223, 255, 255, 0.16) 0 10px, rgba(112, 199, 215, 0.2) 10px 18px, rgba(64, 126, 163, 0.22) 18px 28px); }
.neptune { --size: 21px; --planet-day: 8.5s; --planet-glow: rgba(109, 155, 255, 0.16); --planet-base: radial-gradient(circle at 32% 28%, #9fd2ff 0%, #4376f3 46%, #2349b9 72%, #12235f 100%); --planet-texture: repeating-linear-gradient(90deg, rgba(172, 220, 255, 0.18) 0 10px, rgba(84, 130, 236, 0.24) 10px 18px, rgba(32, 64, 158, 0.26) 18px 28px); }

.planet-chip {
  width: 54px;
  height: 54px;
  margin: 6px 0 14px;
}

.planet-chip .planet-surface {
  box-shadow:
    inset -10px -14px 18px var(--planet-shadow),
    inset 8px 8px 14px rgba(255,255,255,0.1),
    0 0 18px var(--planet-glow);
}

.planet-chip.saturn .planet-ring {
  inset-inline: -24%;
}

.planet-chip-img {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  border-radius: 50%;
  object-fit: cover;
  display: block;
}

.planet-chip .planet-chip-img {
  box-shadow:
    inset -10px -14px 18px rgba(0, 0, 0, 0.46),
    inset 8px 8px 14px rgba(255,255,255,0.1),
    0 0 18px rgba(255,255,255,0.08);
}

/* ========== Section layouts ========== */
.section {
  padding: 46px 0;
}

.section-heading {
  display: grid;
  gap: 12px;
  margin-bottom: 26px;
}

.overview-grid,
.theme-grid,
.knowledge-grid {
  display: grid;
  gap: 18px;
}

.overview-grid {
  grid-template-columns: 1.25fr 0.75fr;
}

.overview-facts {
  display: grid;
  gap: 18px;
}

.panel {
  border-radius: var(--radius);
  padding: 24px;
  transition: transform var(--transition-smooth), border-color var(--transition-smooth), box-shadow var(--transition-smooth);
}

.panel:hover {
  transform: translateY(-2px);
  border-color: rgba(255, 214, 134, 0.18);
}

.feature-panel p:first-child {
  margin-top: 0;
}

.feature-panel p:last-child {
  margin-bottom: 0;
}

.stat-panel span,
.planet-card em {
  color: var(--gold-soft);
}

.stat-panel strong {
  display: block;
  margin-top: 10px;
  font-size: 1.2rem;
  color: var(--text);
}

/* ========== Planet Grid ========== */
.planet-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 18px;
}

.planet-card {
  display: flex;
  flex-direction: column;
  min-height: 240px;
  padding: 22px;
  border-radius: 24px;
  color: var(--text);
  border: 1px solid var(--border);
  background:
    radial-gradient(circle at top right, rgba(255, 183, 74, 0.12), transparent 28%),
    linear-gradient(180deg, rgba(255,255,255,0.05), rgba(255,255,255,0.02)),
    rgba(9, 18, 35, 0.82);
  transition:
    transform 0.35s cubic-bezier(0.34, 1.56, 0.64, 1),
    border-color 180ms ease,
    box-shadow 180ms ease;
  position: relative;
  overflow: hidden;
}

/* Glow effect on hover */
.planet-card::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: 24px;
  opacity: 0;
  transition: opacity 0.4s ease;
  pointer-events: none;
}

.planet-card:hover::before {
  opacity: 1;
}

.planet-card:hover {
  transform: translateY(-6px) scale(1.02);
  border-color: rgba(255, 214, 134, 0.34);
  box-shadow:
    0 24px 48px rgba(0, 0, 0, 0.3),
    0 0 30px rgba(255, 183, 74, 0.10);
  z-index: 2;
}

.planet-card .planet-index {
  order: 0;
}

.planet-card .planet-chip {
  order: 1;
}

.planet-card h3 {
  order: 2;
}

.planet-index {
  display: inline-block;
  margin-bottom: 18px;
  color: var(--blue-soft);
  font-size: 0.84rem;
  letter-spacing: 0.2em;
}

.planet-card p {
  color: var(--muted);
  margin: 14px 0 0;
  flex: 1;
  order: 3;
}

.planet-card em {
  margin-top: 16px;
  font-style: normal;
  order: 4;
  transition: color 180ms ease;
}

.planet-card:hover em {
  color: var(--text);
}

.featured-card {
  border-color: var(--border-strong);
  background:
    radial-gradient(circle at top right, rgba(105, 176, 255, 0.18), transparent 30%),
    radial-gradient(circle at bottom left, rgba(255, 188, 83, 0.12), transparent 26%),
    rgba(10, 21, 40, 0.88);
}

.theme-grid {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

.knowledge-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.theme-card,
.knowledge-card {
  min-height: 220px;
}

.accent-card {
  border-color: var(--border-strong);
}

/* ========== CTA Panel ========== */
.cta-panel {
  display: grid;
  gap: 16px;
  align-items: start;
  background:
    radial-gradient(circle at 85% 20%, rgba(255, 183, 74, 0.16), transparent 24%),
    linear-gradient(180deg, rgba(255,255,255,0.06), rgba(255,255,255,0.02)),
    var(--panel-strong);
}

.cta-panel p {
  margin: 0;
}

/* ========== Footer ========== */
.site-footer {
  width: min(var(--max-width), calc(100% - 32px));
  margin: 16px auto 36px;
  padding-top: 20px;
  display: flex;
  justify-content: space-between;
  gap: 20px;
  flex-wrap: wrap;
  border-top: 1px solid rgba(135, 180, 255, 0.08);
}

.site-footer p {
  margin: 0;
  font-size: 0.94rem;
}

.footer-links {
  display: flex;
  gap: 18px;
  flex-wrap: wrap;
}

.footer-links a {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.94rem;
  transition: color 180ms ease;
}

.footer-links a:hover {
  color: var(--gold-soft);
}

.footer-links a::before {
  content: "·";
  margin-right: 10px;
  color: rgba(255,255,255,0.2);
}

.footer-links a:first-child::before {
  content: "";
  margin-right: 0;
}

/* ========== Back to Top Button ========== */
.back-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  z-index: 100;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  border: 1px solid rgba(255,255,255,0.1);
  background:
    linear-gradient(180deg, rgba(255,255,255,0.08), rgba(255,255,255,0.02)),
    rgba(8, 14, 28, 0.6);
  color: var(--text);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  backdrop-filter: blur(18px) saturate(150%);
  -webkit-backdrop-filter: blur(18px) saturate(150%);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.2);
  opacity: 0;
  transform: translateY(20px) scale(0.8);
  transition:
    opacity 0.3s ease,
    transform 0.3s cubic-bezier(0.34, 1.56, 0.64, 1),
    border-color 180ms ease,
    background 180ms ease;
  pointer-events: none;
}

.back-to-top.is-visible {
  opacity: 1;
  transform: translateY(0) scale(1);
  pointer-events: auto;
}

.back-to-top:hover {
  transform: translateY(-3px) scale(1.05);
  border-color: rgba(255, 215, 145, 0.34);
  background:
    linear-gradient(180deg, rgba(255,255,255,0.1), rgba(255,255,255,0.04)),
    rgba(255, 208, 114, 0.1);
}

/* ========== Scroll Reveal Animations ========== */
[data-reveal] {
  opacity: 0;
  transform: translateY(32px);
  transition:
    opacity 0.8s cubic-bezier(0.4, 0, 0.2, 1),
    transform 0.8s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-reveal].revealed {
  opacity: 1;
  transform: translateY(0);
}

/* Staggered delay for child elements */
[data-reveal-delay="0"] { transition-delay: 0s; }
[data-reveal-delay="1"] { transition-delay: 0.08s; }
[data-reveal-delay="2"] { transition-delay: 0.16s; }
[data-reveal-delay="3"] { transition-delay: 0.24s; }
[data-reveal-delay="4"] { transition-delay: 0.32s; }
[data-reveal-delay="5"] { transition-delay: 0.40s; }
[data-reveal-delay="6"] { transition-delay: 0.48s; }
[data-reveal-delay="7"] { transition-delay: 0.56s; }

/* ========== Page entrance animation ========== */
.hero [data-reveal] {
  transition-delay: 0.15s;
}

/* ========== Planet page specifics ========== */
.planet-page .hero {
  grid-template-columns: 1fr 0.8fr;
  min-height: auto;
  padding-top: 50px;
}

.planet-badge {
  display: inline-flex;
  padding: 8px 14px;
  border-radius: 999px;
  background: rgba(255,255,255,0.05);
  border: 1px solid var(--border);
  color: var(--gold-soft);
  font-size: 0.9rem;
}

.planet-visual {
  width: min(360px, 72vw);
  aspect-ratio: 1 / 1;
  margin-inline: auto;
  position: relative;
  filter: drop-shadow(0 24px 42px rgba(0, 0, 0, 0.34));
}

.planet-3d-shell {
  width: min(460px, 78vw);
  min-height: min(460px, 78vw);
  aspect-ratio: 1 / 1;
  display: grid;
  place-items: center;
}

.planet-img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: 50%;
  box-shadow:
    inset -26px -34px 46px rgba(0, 0, 0, 0.46),
    inset 18px 16px 22px rgba(255,255,255,0.12),
    0 0 64px rgba(255,255,255,0.08);
}

.planet-visual-inner {
  position: relative;
  display: grid;
  place-items: center;
  border-radius: 50%;
  overflow: hidden;
}

.planet-render {
  display: block;
  width: min(420px, 74vw);
  height: auto;
  object-fit: contain;
  filter: drop-shadow(0 30px 54px rgba(0, 0, 0, 0.36));
}





.planet-visual::after {
  content: "";
  position: absolute;
  inset: auto 14% 10% 18%;
  height: 16%;
  border-radius: 50%;
  background: rgba(255,255,255,0.08);
  filter: blur(16px);
}

.detail-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 18px;
}

.detail-grid .panel strong {
  display: block;
  margin-top: 10px;
  font-size: 1.1rem;
}

/* ========== Keyframes ========== */


/* ========== Reduced Motion ========== */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

  .planet-surface::before,
  .viewer-loader-ring,
  .ss-orbit,
  .ss-sun-core,
  .ss-sun-glow,
  .star-field,
  [data-reveal] {
    animation: none !important;
  }

  .viewer-button,
  .button,
  .planet-card,
  .site-nav a,
  .back-to-top,
  [data-reveal] {
    transition: none !important;
  }

  [data-reveal] {
    opacity: 1 !important;
    transform: none !important;
  }
}

/* ========== Responsive: Tablet ========== */
@media (max-width: 1024px) {
  .hero,
  .planet-page .hero {
    grid-template-columns: 1fr;
  }

  .hero-orbit {
    position: relative;
    width: 100%;
    height: auto;
    min-height: 520px;
    order: -1;
  }

  .hero-copy {
    max-width: none;
    padding-right: 0;
  }

  .solar-system {
    height: 520px;
    min-height: 420px;
  }

  .planet-3d-shell {
    width: min(520px, 100%);
    min-height: min(520px, 100vw - 32px);
  }

  .planet-render {
    width: min(440px, 100%);
  }

  .ss-orbit {
    --orbit-size: clamp(8%, 16vw, 80%);
  }
}

/* ========== Responsive: Mobile ========== */
@media (max-width: 720px) {
  .site-header {
    border-radius: 24px;
    align-items: flex-start;
    flex-direction: column;
  }

  .hero {
    padding-top: 40px;
    min-height: auto;
  }

  .hero-orbit {
    order: -1;
    min-height: auto;
  }

  .solar-system {
    min-height: 380px;
  }

  .solar-system {
    min-height: 420px;
  }



  .planet-grid,
  .theme-grid,
  .knowledge-grid,
  .detail-grid {
    grid-template-columns: 1fr;
  }

  .hero-stats {
    flex-direction: column;
  }

  .site-footer {
    flex-direction: column;
  }

  .footer-links a:first-child::before {
    content: "";
    margin-right: 0;
  }

  .back-to-top {
    bottom: 20px;
    right: 20px;
    width: 44px;
    height: 44px;
  }
}