/* ------------------------------------------------------------------
   LRPS Design Study - styles
   Apple-clean: generous whitespace, restrained palette,
   deep-space navy + warm orange accent. Dark default, light toggle.
-------------------------------------------------------------------*/

:root {
  --bg: #05070c;
  --bg-soft: #0a0e16;
  --bg-card: rgba(255,255,255,0.04);
  --bg-card-strong: rgba(255,255,255,0.06);
  --fg: #f2f4f8;
  --fg-mute: #a7adbb;
  --fg-dim: #6b7180;
  --line: rgba(255,255,255,0.09);
  --accent: #ff7a29;
  --accent-soft: rgba(255,122,41,0.14);
  --navy: #2f6bc8;
  --navy-soft: rgba(47,107,200,0.18);
  --radius-lg: 22px;
  --radius-md: 14px;
  --radius-sm: 8px;
  --ease: cubic-bezier(.2,.8,.2,1);
  --maxw: 1180px;

  --f-display: "Inter", -apple-system, BlinkMacSystemFont, "SF Pro Display", "Segoe UI", sans-serif;
  --f-mono: "JetBrains Mono", ui-monospace, "SF Mono", Menlo, monospace;
}

html[data-theme="light"] {
  --bg: #f6f7f9;
  --bg-soft: #ffffff;
  --bg-card: rgba(6,10,20,0.03);
  --bg-card-strong: rgba(6,10,20,0.06);
  --fg: #0b1020;
  --fg-mute: #4c5364;
  --fg-dim: #8b92a1;
  --line: rgba(6,10,20,0.1);
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  font-family: var(--f-display);
  background: var(--bg);
  color: var(--fg);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
  font-feature-settings: "ss01", "cv02", "cv11";
}

::selection { background: var(--accent); color: #fff; }

a { color: inherit; text-decoration: none; }
button { font: inherit; color: inherit; background: none; border: 0; cursor: pointer; }
h1, h2, h3, h4 { font-weight: 600; letter-spacing: -0.02em; }
p { line-height: 1.55; }

/* ------------------------------------------------------------------
   NAV
-------------------------------------------------------------------*/
.nav {
  position: fixed; top: 0; left: 0; right: 0;
  z-index: 50;
  padding: 14px 0;
  background: rgba(5,7,12,0.55);
  backdrop-filter: saturate(160%) blur(18px);
  -webkit-backdrop-filter: saturate(160%) blur(18px);
  border-bottom: 1px solid transparent;
  transition: background .3s var(--ease), border-color .3s var(--ease);
}
html[data-theme="light"] .nav { background: rgba(246,247,249,0.7); }
.nav.is-scrolled { border-bottom-color: var(--line); }

.nav-inner {
  max-width: var(--maxw); margin: 0 auto; padding: 0 28px;
  display: flex; align-items: center; gap: 28px;
}
.nav-brand {
  display: flex; align-items: center; gap: 10px;
  font-weight: 700; letter-spacing: -0.01em; font-size: 15px;
}
.nav-brand-thin { font-weight: 400; color: var(--fg-mute); }
.nav-dot {
  width: 10px; height: 10px; border-radius: 50%;
  background: var(--accent); box-shadow: 0 0 18px var(--accent);
}

.nav-links {
  list-style: none; padding: 0; margin: 0 auto 0 16px;
  display: flex; gap: 28px; font-size: 13.5px; color: var(--fg-mute);
}
.nav-links a { transition: color .2s var(--ease); }
.nav-links a:hover { color: var(--fg); }

.nav-theme {
  width: 36px; height: 36px; border-radius: 50%;
  display: grid; place-items: center;
  background: var(--bg-card); color: var(--fg-mute);
  transition: background .2s var(--ease), color .2s var(--ease);
}
.nav-theme:hover { background: var(--bg-card-strong); color: var(--fg); }

@media (max-width: 720px) {
  .nav-links { display: none; }
}

/* ------------------------------------------------------------------
   HERO
-------------------------------------------------------------------*/
.hero {
  position: relative;
  min-height: 100vh;
  display: flex; flex-direction: column; justify-content: center; align-items: center;
  padding: 160px 28px 80px;
  overflow: hidden;
  isolation: isolate;
}
.hero-canvas {
  position: absolute; inset: 0; width: 100%; height: 100%;
  z-index: -1; opacity: 0.9;
}
.hero::after {
  content: ""; position: absolute; inset: 0;
  background: radial-gradient(ellipse at 50% 40%, transparent 0%, var(--bg) 85%);
  pointer-events: none; z-index: -1;
}

.hero-content {
  max-width: 920px; text-align: center;
}
.hero-eyebrow {
  font-size: 12.5px; letter-spacing: 0.22em; text-transform: uppercase;
  color: var(--fg-mute); margin-bottom: 28px;
}
.hero-title {
  font-size: clamp(64px, 11vw, 156px);
  line-height: 0.95; letter-spacing: -0.045em;
  margin: 0 0 24px; font-weight: 700;
}
.hero-title-line { display: block; overflow: hidden; }
.hero-title-accent {
  background: linear-gradient(92deg, #ffb27a 0%, var(--accent) 55%, #ff4e8f 100%);
  -webkit-background-clip: text; background-clip: text; color: transparent;
}
.hero-sub {
  font-size: clamp(17px, 1.6vw, 21px);
  color: var(--fg-mute); max-width: 620px; margin: 0 auto 56px;
}

.hero-stats {
  display: grid; grid-template-columns: repeat(3, 1fr);
  gap: 12px; max-width: 760px; margin: 0 auto;
}
.hero-stats > div {
  padding: 20px 10px;
  border-left: 1px solid var(--line);
}
.hero-stats > div:first-child { border-left: 0; }
.hero-stats span {
  display: block; font-size: clamp(22px, 2.4vw, 30px); font-weight: 600;
  letter-spacing: -0.02em; color: var(--fg);
}
.hero-stats em {
  display: block; margin-top: 6px; font-style: normal;
  font-size: 12px; color: var(--fg-dim); letter-spacing: 0.1em; text-transform: uppercase;
}

.hero-scroll {
  position: absolute; bottom: 36px; left: 50%; transform: translateX(-50%);
  display: flex; flex-direction: column; align-items: center; gap: 10px;
  font-size: 11px; letter-spacing: 0.24em; text-transform: uppercase;
  color: var(--fg-dim); opacity: 0.8;
  transition: color .2s var(--ease);
}
.hero-scroll:hover { color: var(--fg); }

/* ------------------------------------------------------------------
   SECTIONS
-------------------------------------------------------------------*/
.section {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 160px 28px;
}
.section-eyebrow {
  font-size: 12px; letter-spacing: 0.24em; text-transform: uppercase;
  color: var(--accent); margin-bottom: 28px;
  font-weight: 500;
}
.section-title {
  font-size: clamp(40px, 5.2vw, 76px);
  line-height: 1.02; letter-spacing: -0.035em;
  margin: 0 0 40px; max-width: 920px;
}
.section-lede {
  font-size: clamp(17px, 1.35vw, 20px);
  color: var(--fg-mute); max-width: 720px; margin: 0 0 64px;
}

/* MISSION GIVENS */
.givens {
  margin-top: 40px;
  padding: 48px;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--bg-card);
}
.givens h3 {
  font-size: 13px; letter-spacing: 0.24em; text-transform: uppercase;
  color: var(--fg-mute); margin: 0 0 32px; font-weight: 500;
}
.givens-grid {
  list-style: none; padding: 0; margin: 0;
  display: grid; grid-template-columns: repeat(5, 1fr); gap: 24px 32px;
}
.givens-grid li {
  border-top: 1px solid var(--line); padding-top: 16px;
}
.givens-grid span {
  display: block; font-family: var(--f-mono); font-size: 11px;
  color: var(--fg-dim); letter-spacing: 0.08em; text-transform: uppercase;
  margin-bottom: 8px;
}
.givens-grid strong {
  display: block; font-size: 17px; font-weight: 500; letter-spacing: -0.01em;
}
@media (max-width: 900px) { .givens-grid { grid-template-columns: repeat(2, 1fr); } .givens { padding: 28px; } }

/* ------------------------------------------------------------------
   TRANSFER
-------------------------------------------------------------------*/
.transfer-stage {
  position: relative;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: radial-gradient(ellipse at 30% 20%, rgba(47,107,200,0.08) 0%, transparent 60%), var(--bg-soft);
  padding: 32px;
  overflow: hidden;
}
.transfer-svg {
  width: 100%; height: auto; display: block;
  max-height: 620px;
}

/* orbit lines */
.orbit-geo, .orbit-lunar {
  fill: none; stroke: var(--line);
  stroke-width: 1.2;
  stroke-dasharray: 3 4;
}
.orbit-transfer {
  fill: none; stroke: var(--accent);
  stroke-width: 1.6;
  stroke-dasharray: 1000;
  stroke-dashoffset: 1000;
  opacity: 0.9;
  filter: drop-shadow(0 0 8px rgba(255,122,41,0.45));
}

.orbit-label text {
  fill: var(--fg-dim);
  font-family: var(--f-mono); font-size: 12px;
  text-transform: uppercase; letter-spacing: 0.12em;
}

/* burns */
.burn line { stroke: var(--accent); stroke-width: 3; }
.burn polygon { fill: var(--accent); }
.burn-label text {
  fill: var(--accent);
  font-family: var(--f-display); font-weight: 600; font-size: 16px;
}
.burn-label .burn-label-val {
  fill: var(--fg-mute); font-weight: 400; font-size: 12px;
  font-family: var(--f-mono); letter-spacing: 0.04em;
}
.burn { opacity: 0; }
.burn.is-active { opacity: 1; transition: opacity .3s var(--ease); }

.craft { filter: drop-shadow(0 0 10px rgba(255,122,41,0.6)); }

#stars circle { fill: var(--fg-dim); opacity: 0.5; }
html[data-theme="light"] #stars circle { opacity: 0.18; }
html[data-theme="light"] .orbit-geo,
html[data-theme="light"] .orbit-lunar { stroke: rgba(6,10,20,0.18); }

.transfer-controls {
  display: flex; align-items: center; justify-content: space-between;
  gap: 24px; margin-top: 24px; flex-wrap: wrap;
}
.play-btn {
  display: inline-flex; align-items: center; gap: 10px;
  padding: 12px 22px; border-radius: 999px;
  background: var(--accent); color: #1a0a02;
  font-weight: 600; font-size: 14px;
  transition: transform .15s var(--ease), box-shadow .2s var(--ease);
  box-shadow: 0 6px 24px rgba(255,122,41,0.35);
}
.play-btn:hover { transform: translateY(-1px); box-shadow: 0 10px 30px rgba(255,122,41,0.45); }
.play-btn:active { transform: translateY(0); }

.transfer-readout {
  display: flex; gap: 36px;
  font-family: var(--f-mono); font-size: 12px; color: var(--fg-dim);
}
.transfer-readout em {
  display: block; font-style: normal;
  letter-spacing: 0.14em; text-transform: uppercase; font-size: 10px;
  margin-bottom: 4px;
}
.transfer-readout span { color: var(--fg); font-size: 14px; }

/* ------------------------------------------------------------------
   EQUATIONS
-------------------------------------------------------------------*/
.eq-list { list-style: none; padding: 0; margin: 0; display: grid; gap: 20px; }
.eq {
  display: grid; grid-template-columns: 1.15fr 1fr; gap: 48px; align-items: center;
  padding: 40px 44px;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--bg-card);
  transition: border-color .3s var(--ease), transform .4s var(--ease);
}
.eq:hover { border-color: rgba(255,122,41,0.35); }
.eq-render {
  font-size: clamp(18px, 1.8vw, 24px);
  overflow-x: auto;
}
.eq-render .katex { color: var(--fg); }
.eq-body h4 {
  font-size: 11.5px; letter-spacing: 0.22em; text-transform: uppercase;
  color: var(--accent); margin: 0 0 14px; font-weight: 500;
}
.eq-body p { margin: 0; color: var(--fg-mute); font-size: 16px; }

@media (max-width: 900px) {
  .eq { grid-template-columns: 1fr; gap: 24px; padding: 28px; }
}

/* ------------------------------------------------------------------
   RESULTS
-------------------------------------------------------------------*/
.results-group {
  padding: 56px 0;
  border-top: 1px solid var(--line);
}
.results-group:first-of-type { border-top: 0; padding-top: 0; }
.results-group h3 {
  font-size: 12px; letter-spacing: 0.26em; text-transform: uppercase;
  color: var(--fg-mute); margin: 0 0 40px; font-weight: 500;
}
.results-group.accent h3 { color: var(--accent); }

.stat-grid {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px;
}
.stat {
  padding: 32px 28px;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: var(--bg-card);
  transition: transform .3s var(--ease), border-color .3s var(--ease), background .3s var(--ease);
}
.stat:hover { transform: translateY(-3px); border-color: rgba(255,122,41,0.35); background: var(--bg-card-strong); }
.stat.big { grid-column: span 2; background: linear-gradient(135deg, var(--accent-soft), transparent 70%), var(--bg-card); }
.stat-val {
  font-size: clamp(36px, 4.2vw, 56px);
  font-weight: 600; letter-spacing: -0.03em;
  line-height: 1; font-variant-numeric: tabular-nums;
}
.stat-unit {
  display: inline-block; margin-left: 8px;
  font-size: 15px; color: var(--fg-dim); font-weight: 400;
  vertical-align: middle;
}
.stat-label {
  margin-top: 14px; color: var(--fg-mute); font-size: 13px;
  letter-spacing: 0.04em;
}
@media (max-width: 900px) {
  .stat-grid { grid-template-columns: repeat(2, 1fr); }
  .stat.big { grid-column: span 2; }
}

/* SPLIT bars */
.split {
  display: grid; gap: 28px; padding: 8px 0 0;
}
.split-row {
  display: grid; grid-template-columns: 220px 1fr; gap: 32px; align-items: center;
}
.split-head {
  display: flex; align-items: center; gap: 12px;
  font-size: 15px; color: var(--fg);
}
.split-dot {
  width: 10px; height: 10px; border-radius: 50%;
}
.lox .split-dot { background: #20c0a8; box-shadow: 0 0 12px rgba(32,192,168,0.5); }
.lh2 .split-dot { background: #2f6bc8; box-shadow: 0 0 12px rgba(47,107,200,0.5); }

.split-bars {
  display: grid; grid-template-columns: 1fr 1fr; gap: 16px;
}
.bar {
  position: relative;
  height: 46px; border-radius: 8px;
  background: var(--bg-card);
  border: 1px solid var(--line);
  overflow: hidden;
  display: flex; align-items: center; padding: 0 14px;
  gap: 8px;
  font-family: var(--f-mono); font-size: 13px;
}
.bar::before {
  content: ""; position: absolute; inset: 0;
  width: 0%;
  background: linear-gradient(90deg, rgba(47,107,200,0.35), rgba(32,192,168,0.25));
  transition: width 1.4s var(--ease);
}
.lox .bar::before { background: linear-gradient(90deg, rgba(32,192,168,0.45), rgba(32,192,168,0.12)); }
.lh2 .bar::before { background: linear-gradient(90deg, rgba(47,107,200,0.45), rgba(47,107,200,0.12)); }
.bar em { font-style: normal; font-weight: 600; color: var(--fg); position: relative; }
.bar span { color: var(--fg-dim); position: relative; font-size: 11px; }
.bar.is-filled::before { width: var(--fill, 0%); }

.split-legend {
  display: grid; grid-template-columns: 220px 1fr 1fr; gap: 32px;
  padding-top: 4px;
  font-size: 11px; color: var(--fg-dim); letter-spacing: 0.16em; text-transform: uppercase;
}
.split-legend span:first-child { grid-column: 2; }
@media (max-width: 760px) {
  .split-row { grid-template-columns: 1fr; }
  .split-legend { grid-template-columns: 1fr 1fr; }
  .split-legend span:first-child { grid-column: 1; }
}

/* ------------------------------------------------------------------
   VEHICLE
-------------------------------------------------------------------*/
.rocket-stage {
  display: grid; grid-template-columns: minmax(320px, 480px) 1fr;
  gap: 80px; align-items: center;
  margin-top: 48px;
}
.rocket-svg { width: 100%; height: auto; }
.svg-label-inside { fill: #0b1020; font-size: 12px; font-weight: 600; font-family: var(--f-display); }
.svg-label-inside-sub { fill: #4c5364; font-size: 10px; font-family: var(--f-mono); letter-spacing: 0.08em; text-transform: uppercase; }
.svg-label-tank { fill: #fff; font-size: 22px; font-weight: 600; font-family: var(--f-display); }
.svg-label-tank-sub { fill: rgba(255,255,255,0.8); font-size: 11px; font-family: var(--f-mono); letter-spacing: 0.08em; }

.callout line { stroke: var(--fg-dim); stroke-width: 1; }
.callout circle { fill: var(--accent); }
.callout text { fill: var(--fg); font-family: var(--f-display); font-size: 13px; font-weight: 500; }
.callout .callout-sub { fill: var(--fg-mute); font-family: var(--f-mono); font-size: 10.5px; letter-spacing: 0.08em; }

.vehicle-note p { font-size: 17px; color: var(--fg-mute); line-height: 1.65; }
.vehicle-note strong { color: var(--fg); font-weight: 600; }

@media (max-width: 900px) {
  .rocket-stage { grid-template-columns: 1fr; gap: 40px; }
}

/* ------------------------------------------------------------------
   FOOTER
-------------------------------------------------------------------*/
.footer {
  border-top: 1px solid var(--line);
  padding: 64px 28px 40px;
  margin-top: 80px;
}
.footer-inner {
  max-width: var(--maxw); margin: 0 auto;
  display: flex; justify-content: space-between; align-items: center;
  gap: 24px; flex-wrap: wrap;
}
.footer-brand { font-weight: 600; font-size: 17px; letter-spacing: -0.01em; }
.footer-meta { margin-top: 4px; color: var(--fg-mute); font-size: 13px; }
.footer-links {
  display: flex; gap: 14px; color: var(--fg-mute); font-size: 13.5px;
}
.footer-links a { transition: color .2s var(--ease); }
.footer-links a:hover { color: var(--accent); }
.footer-legal {
  max-width: var(--maxw); margin: 40px auto 0;
  color: var(--fg-dim); font-size: 12px; letter-spacing: 0.02em;
}

/* ------------------------------------------------------------------
   REVEAL ANIMATIONS (GSAP will toggle)
-------------------------------------------------------------------*/
.reveal { opacity: 0; transform: translateY(26px); }
.reveal.is-visible { opacity: 1; transform: none; transition: opacity 1s var(--ease), transform 1s var(--ease); }