:root{
  --sky-top:#a9c7e8; --sky-bot:#eef4fb;
  --slate:#B0C4DE; --slate-light:#E2E8F0;
  --rose:#D2C2C0; --rose-light:#ECE2E1;
  --accent:#7D5C58; --accent-2:#B29692;
  --cream:#F7F3F0; --ink:#1f2733; --muted:#5b6573;
  --maxw:1080px; --radius:16px;
  --shadow:0 10px 40px -12px rgba(31,39,51,.18);
  --serif:"Fraunces",Georgia,serif; --sans:"Inter",system-ui,sans-serif;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;font-family:var(--sans);color:var(--ink);background:var(--cream);line-height:1.6;-webkit-font-smoothing:antialiased}
h1,h2,h3{font-family:var(--serif);font-weight:600;line-height:1.1;letter-spacing:-.01em}
a{color:var(--accent);text-decoration:none}
img{max-width:100%;display:block}
.section{padding:96px 24px}
.section--tint{background:linear-gradient(180deg,var(--rose-light),var(--cream))}
.wrap{max-width:var(--maxw);margin:0 auto}
.eyebrow{font-family:var(--sans);font-weight:600;letter-spacing:.14em;text-transform:uppercase;font-size:.72rem;color:var(--accent)}
.section h2{font-size:clamp(1.8rem,3.4vw,2.6rem);margin:.2em 0 .4em}
.lead{font-size:1.12rem;color:var(--muted);max-width:62ch}
.btn{display:inline-flex;align-items:center;gap:.5em;padding:.7em 1.25em;border-radius:999px;font-weight:600;font-family:var(--sans);border:1px solid transparent;transition:transform .15s ease,box-shadow .15s ease;cursor:pointer}
.btn:hover{transform:translateY(-2px)}
.btn--primary{background:var(--accent);color:#fff;box-shadow:var(--shadow)}
.btn--ghost{background:rgba(255,255,255,.7);color:var(--ink);border-color:rgba(31,39,51,.12);backdrop-filter:blur(6px)}
.card{background:#fff;border-radius:var(--radius);box-shadow:var(--shadow);border:1px solid rgba(31,39,51,.05)}
/* scroll reveal — only hidden when JS is active (progressive enhancement) */
.js .reveal{opacity:0;transform:translateY(12px);transition:opacity .6s ease,transform .6s ease}
.js .reveal.is-visible{opacity:1;transform:none}
@media (prefers-reduced-motion: reduce){
  html{scroll-behavior:auto}
  .js .reveal{opacity:1;transform:none;transition:none}
  .btn:hover{transform:none}
}
@media print{ .js .reveal{opacity:1 !important;transform:none !important} }
@media (max-width:720px){ .section{padding:64px 18px} }

/* ===== Nav (Task 4) ===== */
#nav{position:fixed;top:0;left:0;right:0;z-index:50;transition:background .3s ease,box-shadow .3s ease}
.nav-inner{display:flex;align-items:center;justify-content:space-between;padding:14px 24px}
.brand{font-family:var(--serif);font-weight:700;font-size:1.02rem;color:var(--ink);white-space:nowrap}
.nav-links{display:flex;align-items:center;gap:18px}
.nav-links a{color:var(--ink);font-weight:500;font-size:.95rem}
.btn--sm{padding:.45em .9em;font-size:.85rem}
#nav.scrolled{background:rgba(247,243,240,.85);backdrop-filter:blur(10px);box-shadow:0 1px 0 rgba(31,39,51,.06)}
#nav:not(.scrolled) .brand,
#nav:not(.scrolled) .nav-links a:not(.btn){color:var(--ink)}
#nav:not(.scrolled) .btn--ghost{background:rgba(255,255,255,.7);color:var(--ink);border-color:rgba(31,39,51,.12)}
@media (max-width:720px){ .nav-links a:not(.btn){display:none} .author-block{white-space:normal} }

/* ===== Hero (Task 5) ===== */
#hero{position:relative;min-height:100vh;display:flex;align-items:center;overflow:hidden;background:#eef4f8}
.hero-bg{position:absolute;inset:0;background:url('../static/teaser2.png') center/cover no-repeat}
.hero-bg::after{content:'';position:absolute;inset:0;background:rgba(255,255,255,.42)}
.hero-content{position:relative;z-index:2;text-align:center;padding:0 24px;margin:0 auto}
.hero-pill{display:inline-block;background:rgba(255,255,255,.65);padding:.4em 1em;border-radius:999px;backdrop-filter:blur(6px)}
#hero h1{font-size:clamp(2.4rem,6vw,4.6rem);margin:.25em 0 .1em;color:#1a2740}
.hero-sub{font-family:var(--serif);font-size:clamp(1.5rem,3.2vw,2.2rem);color:#33425f;margin:.25em 0 .15em;font-weight:600}
.hero-hook{max-width:60ch;margin:1em auto;color:#3c4a63;font-size:1.05rem}
.hero-cta{display:flex;gap:14px;justify-content:center;align-items:center;flex-wrap:wrap;margin:1.4em 0 1em}
.hero-demo{font-weight:600;color:#33425f}
#hero .btn--ghost{background:rgba(255,255,255,.75);color:var(--ink);border-color:rgba(31,39,51,.12);backdrop-filter:blur(8px)}
.hero-authors{margin:.8em auto 1.4em;max-width:920px}
.author-line{line-height:1.85;font-size:clamp(.88rem,1.6vw,1.05rem);color:#46566f}
.author-line + .author-line{margin-top:.15em}
.author-block{white-space:nowrap}
.hero-authors a{color:var(--accent);font-weight:500;border-bottom:1px solid rgba(125,92,88,.35);transition:border-color .15s ease,color .15s ease}
.hero-authors a:hover{color:var(--accent-2);border-bottom-color:var(--accent-2)}
.hero-chips{list-style:none;display:flex;gap:10px;justify-content:center;flex-wrap:wrap;padding:0;margin:0}
.hero-chips li{background:rgba(255,255,255,.72);border:1px solid rgba(255,255,255,.85);padding:.5em 1em;border-radius:999px;font-size:.9rem;color:#33425f;backdrop-filter:blur(6px)}
.hero-chips b{color:var(--accent)}
.scroll-cue{position:absolute;bottom:22px;left:50%;transform:translateX(-50%);font-size:1.6rem;color:#33425f;z-index:2;animation:bob 2s ease-in-out infinite}
@keyframes bob{50%{transform:translate(-50%,8px)}}
@media (prefers-reduced-motion: reduce){ .scroll-cue{animation:none} }

/* ===== Intro (Task 6) ===== */
.intro-stack{display:flex;flex-direction:column;gap:36px}
#intro .lead{display:block;margin-left:auto;margin-right:auto;text-align:center}
.abstract-card{padding:30px 34px}
.abstract-card h3{margin:.1em 0 .6em;font-size:1.2rem;color:var(--accent)}
.abstract-body{font-size:.97rem;color:var(--muted);margin:0;column-count:2;column-gap:44px;text-align:justify;hyphens:auto}
@media (max-width:820px){ .abstract-body{column-count:1} }

/* ===== Stat band (Task 7) ===== */
.stat-grid{list-style:none;padding:0;margin:40px 0 0;display:grid;grid-template-columns:repeat(5,1fr);gap:18px}
.stat-grid li{padding:26px 18px;text-align:center}
.stat-num{display:block;font-family:var(--serif);font-weight:700;font-size:2.2rem;color:var(--accent)}
.stat-cap{display:block;margin-top:.5em;font-size:.85rem;color:var(--muted)}
@media (max-width:900px){ .stat-grid{grid-template-columns:repeat(2,1fr)} }
@media (max-width:520px){ .stat-grid{grid-template-columns:1fr} }

/* ===== Method (Task 8) ===== */
.method-fig{margin:40px 0;background:#fff;border-radius:var(--radius);box-shadow:var(--shadow);padding:24px;border:1px solid rgba(31,39,51,.05)}
.method-fig img{margin:0 auto}
figcaption{font-size:.85rem;color:var(--muted);margin-top:14px;text-align:center;max-width:80ch;margin-inline:auto}
.steps{list-style:none;padding:0;margin:8px 0 0;display:grid;grid-template-columns:repeat(4,1fr);gap:18px}
.steps li{padding:24px 20px}
.step-n{display:inline-grid;place-items:center;width:34px;height:34px;border-radius:50%;background:var(--rose);color:var(--accent);font-weight:700;font-family:var(--serif);margin-bottom:10px}
.steps h3{font-size:1.05rem;margin:.2em 0 .4em}
.steps p{font-size:.9rem;color:var(--muted);margin:0}
.interp-grid{display:grid;grid-template-columns:1fr 1fr;gap:22px;margin-top:24px}
.interp-card{padding:26px 28px;display:flex;flex-direction:column}
.interp-title{font-size:1.12rem;margin:0 0 .35em;color:var(--ink)}
.interp-text{font-size:.92rem;color:var(--muted);margin:0 0 18px}
.interp-card img{margin:auto auto 0;max-height:230px;width:auto}
@media (max-width:900px){ .steps{grid-template-columns:repeat(2,1fr)} .interp-grid{grid-template-columns:1fr} }

/* ===== Results (Task 9) ===== */
.res-h{font-size:1.15rem;margin:44px 0 14px;color:var(--ink)}
.table-wrap{overflow-x:auto;padding:8px}
table.data{border-collapse:collapse;width:100%;font-size:.85rem}
table.data th,table.data td{padding:9px 10px;text-align:center;border-bottom:1px solid rgba(31,39,51,.08);white-space:nowrap}
table.data th:first-child,table.data td:first-child{text-align:left;font-weight:500}
table.data thead th{font-family:var(--sans);font-weight:600;color:var(--muted);font-size:.78rem}
table.data tr.rcp-row{background:var(--rose-light)}
table.data tr.rcp-row td{color:var(--accent);font-weight:600}
.rw-grid{display:grid;grid-template-columns:1.2fr 1fr;gap:18px;align-items:start}
@media (max-width:900px){ .rw-grid{grid-template-columns:1fr} }

/* ===== Video comparison (Task 10) ===== */
.vc{margin-top:36px}
.vc-tabs,.vc-methods,.vc-toggle{display:flex;gap:8px;flex-wrap:wrap}
.vc-tabs{justify-content:center}
.vc-tabs button,.vc-methods button,.vc-toggle button{font-family:var(--sans);font-weight:600;font-size:.9rem;padding:.5em 1em;border-radius:999px;border:1px solid rgba(31,39,51,.14);background:#fff;color:var(--ink);cursor:pointer;transition:all .15s ease}
.vc-tabs button[aria-selected="true"]{background:var(--accent);color:#fff;border-color:var(--accent)}
.vc-methods button[aria-selected="true"]{background:var(--slate);border-color:var(--slate);color:#1a2740}
.vc-toggle button[aria-pressed="true"]{background:var(--rose);border-color:var(--accent-2);color:var(--accent)}
.vc-toggle button[disabled]{opacity:.35;cursor:not-allowed}
.vc-baseline{display:flex;align-items:center;gap:12px;justify-content:center;margin:16px 0}
.vc-baseline>span{color:var(--muted);font-size:.9rem}
.vc-stage{display:grid;grid-template-columns:1fr 1fr;gap:18px;margin-top:18px}
.vc-side{margin:0;background:#0e1320;border-radius:var(--radius);overflow:hidden;box-shadow:var(--shadow)}
.vc-head{display:flex;align-items:center;gap:10px;padding:12px 16px;color:#fff;background:#141b2d}
.vc-name{font-weight:600}
.vc-badge{font-size:.7rem;background:var(--accent);padding:.2em .6em;border-radius:999px}
.vc-rate{margin-left:auto;font-size:.85rem;color:#aab6cc}
.vc-side video{width:100%;display:block;aspect-ratio:16/9;background:#000;object-fit:cover}
.vc-toggle{padding:12px 16px;background:#141b2d;justify-content:center}
.vc-note{text-align:center;color:var(--muted);font-size:.9rem;margin-top:16px;min-height:1.2em}
@media (max-width:820px){ .vc-stage{grid-template-columns:1fr} }

/* ===== Footer (Task 11) ===== */
#footer{background:var(--ink);color:#cdd6e4;text-align:center;padding:18px 24px 56px}
.footer-visitors{display:flex;justify-content:center;align-items:center;padding:0 0 12px}
.footer-visitors a{display:inline-block;flex-shrink:0}
.footer-visitors img{width:120px;height:auto;max-width:none;display:block}
.foot-title{font-family:var(--serif);font-size:1.15rem;color:#fff;margin:0 0 .3em}
.foot-sub{color:#9fb0c9;max-width:60ch;margin:.2em auto 1em;font-size:.92rem}
.foot-meta a{color:var(--rose)}
.foot-credit{color:#6f7f99;font-size:.8rem;margin-top:1.4em}

/* ===== Print polish ===== */
@media print{ #nav{position:static;background:#fff;box-shadow:none} #hero{min-height:auto} }

/* ===== How it works (explainer video) ===== */
.how-stage{margin-top:36px;background:#fff;border-radius:var(--radius);box-shadow:var(--shadow);border:1px solid rgba(31,39,51,.05);padding:18px}
#how-video{width:100%;max-width:1000px;display:block;margin:0 auto;border-radius:10px;background:#fff;aspect-ratio:16/9}

/* ===== Simulation rollouts gallery ===== */
.sim-group{margin-top:26px}
.sim-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:16px;margin-top:14px}
.sim-card{margin:0;padding:0;overflow:hidden}
.sim-card video{width:100%;display:block;aspect-ratio:4/3;object-fit:cover;background:#0e1320}
.sim-card figcaption{font-size:.82rem;color:var(--muted);text-align:center;padding:10px 8px;font-weight:500}
@media (max-width:900px){ .sim-grid{grid-template-columns:repeat(3,1fr)} }
@media (max-width:620px){ .sim-grid{grid-template-columns:repeat(2,1fr)} }