/* historyfast.com — DESIGN SYSTEM partagé (tokens + composants)
   Référence vivante : site/pages/atmosphere-climat/index.html
   Doc : docs/DESIGN-SYSTEM.md */

:root{
  --ink:#f4ece0; --ink-dim:#b9ad9b; --ink-faint:#7d7364;
  --void:#0a0805; --void-2:#120d09; --panel:#140e07;
  --lava:#ff5a1f; --lava-2:#ff8a3d; --ember:#d63a12; --sun:#ffb547;
  --ice:#9fd6e8; --ice-2:#dff2f7; --leaf:#7fd08a;
  --line:rgba(244,236,224,.14); --line-2:rgba(244,236,224,.07);
  --serif:"Fraunces",Georgia,serif; --read:"Newsreader",Georgia,serif; --mono:"IBM Plex Mono",ui-monospace,monospace;
}
*{margin:0;padding:0;box-sizing:border-box}
html{scroll-behavior:smooth}
body{background:var(--void);color:var(--ink);font-family:var(--read);
  font-size:clamp(1.02rem,.55rem + .75vw,1.22rem);line-height:1.72;font-weight:340;
  -webkit-font-smoothing:antialiased;overflow-x:hidden}
body::before{content:"";position:fixed;inset:0;z-index:9999;pointer-events:none;opacity:.045;
  background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='120' height='120'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.9' numOctaves='2'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");mix-blend-mode:overlay}
a{color:inherit}
.rail{position:fixed;top:0;left:0;height:3px;width:0;z-index:9998;
  background:linear-gradient(90deg,var(--sun),var(--lava),var(--ember),var(--ice));box-shadow:0 0 18px rgba(255,90,31,.5)}

/* ---------- HERO ---------- */
.hero{position:relative;min-height:100svh;display:grid;place-items:center;padding:6rem 6vw 4rem;overflow:hidden;text-align:center;
  background:radial-gradient(120% 80% at 50% -10%,#2a1608 0%,#140b05 42%,#070502 100%)}
#heroSun{position:absolute;top:44%;left:50%;transform:translate(-50%,-50%);width:min(760px,92vw);height:min(760px,92vw);z-index:0;opacity:.85;filter:saturate(1.05)}
.hero::after{content:"";position:absolute;inset:0;z-index:1;pointer-events:none;
  background:radial-gradient(circle at 50% 44%,rgba(10,8,5,.15) 0%,rgba(10,8,5,.55) 34%,rgba(7,5,2,.82) 62%,#070502 100%)}
.hero .stars{position:absolute;inset:0;z-index:0;opacity:.5;
  background-image:radial-gradient(1px 1px at 20% 30%,#fff,transparent),radial-gradient(1px 1px at 70% 22%,#ffe,transparent),radial-gradient(1px 1px at 44% 68%,#fff,transparent),radial-gradient(1.4px 1.4px at 85% 55%,#fff,transparent),radial-gradient(1px 1px at 12% 80%,#fff,transparent),radial-gradient(1px 1px at 60% 88%,#fff,transparent)}
.hero-inner{position:relative;z-index:2;max-width:1000px}
.kicker{font-family:var(--mono);font-size:.72rem;letter-spacing:.42em;text-transform:uppercase;color:var(--sun);margin-bottom:2.2rem;opacity:0;animation:rise .9s .1s forwards}
.hero h1{font-family:var(--serif);font-weight:400;font-optical-sizing:auto;font-size:clamp(2.6rem,1rem + 7vw,6.6rem);line-height:.98;letter-spacing:-.015em;text-wrap:balance;margin-bottom:1.6rem}
.hero h1 em{font-style:italic;color:var(--lava-2)}
.hero h1 .l1{display:block;opacity:0;animation:rise 1s .25s forwards}
.hero h1 .l2{display:block;opacity:0;animation:rise 1s .42s forwards}
.hero .lede{font-size:clamp(1.05rem,.7rem + .8vw,1.4rem);color:var(--ink-dim);max-width:44ch;margin:0 auto 2.6rem;font-weight:320;opacity:0;animation:rise 1s .6s forwards}
.hero .meta{font-family:var(--mono);font-size:.74rem;letter-spacing:.12em;color:var(--ink-faint);display:flex;gap:1.4rem;justify-content:center;flex-wrap:wrap;opacity:0;animation:rise 1s .78s forwards}
.hero .meta b{color:var(--ink-dim);font-weight:500}
.scrollcue{position:absolute;bottom:2rem;left:50%;transform:translateX(-50%);z-index:2;font-family:var(--mono);font-size:.66rem;letter-spacing:.3em;color:var(--ink-faint);writing-mode:vertical-rl;opacity:0;animation:rise 1s 1s forwards,float 2.4s 1.6s ease-in-out infinite}
@keyframes rise{from{opacity:0;transform:translateY(26px)}to{opacity:1;transform:none}}
@keyframes float{50%{transform:translateX(-50%) translateY(8px)}}

/* ---------- LAYOUT ---------- */
main{position:relative;max-width:1300px;margin:0 auto;padding:0 clamp(1.1rem,5vw,3.4rem)}
.section{padding:clamp(3.2rem,9vh,8rem) 0;position:relative}
.section + .section{border-top:1px solid var(--line-2)}
.era-tag{font-family:var(--mono);font-size:.72rem;letter-spacing:.2em;text-transform:uppercase;color:var(--lava-2);display:inline-flex;align-items:center;gap:.7rem;margin-bottom:1.6rem}
.era-tag::before{content:"";width:34px;height:1px;background:var(--lava);display:inline-block}
.era-tag.cold{color:var(--ice)}.era-tag.cold::before{background:var(--ice)}
.era-tag.leaf{color:var(--leaf)}.era-tag.leaf::before{background:var(--leaf)}
h2{font-family:var(--serif);font-weight:380;font-size:clamp(1.9rem,1rem + 3vw,3.4rem);line-height:1.04;letter-spacing:-.01em;margin-bottom:1.5rem;text-wrap:balance}
h2 em{font-style:italic;color:var(--sun)}
.section p{margin-bottom:1.15rem;max-width:66ch}
.section p .dim{color:var(--ink-dim)}
strong{font-weight:600;color:#fff}
.lead-p{font-size:1.16em;color:var(--ink);font-weight:360}
.grid{display:grid;grid-template-columns:repeat(12,1fr);gap:clamp(1.6rem,4vw,4rem);align-items:center}
.grid>div{grid-column:span 5;min-width:0}
.grid>figure{grid-column:span 7;min-width:0}
.grid.two-viz>figure{grid-column:span 6}
@media(max-width:860px){
  .grid{grid-template-columns:1fr;gap:1.7rem}
  .grid>div,.grid>figure{grid-column:auto!important}
}

/* viz frame */
.viz{position:relative;border:1px solid var(--line);border-radius:10px;overflow:hidden;background:linear-gradient(160deg,var(--void-2),#0c0a07);box-shadow:0 30px 70px -34px rgba(0,0,0,.9),inset 0 1px 0 rgba(255,255,255,.03)}
.viz .stage{position:relative;width:100%;aspect-ratio:3/2;max-height:76vh;display:block}
.viz .stage.square{aspect-ratio:1/1}
.viz .stage.tall{aspect-ratio:4/3}
@media(max-width:860px){.viz .stage{aspect-ratio:4/3;max-height:none}.viz .stage.square{aspect-ratio:1/1}}
@media(max-width:520px){.viz .stage,.viz .stage.tall{aspect-ratio:5/4}}
.viz canvas,.viz svg{position:absolute;inset:0;width:100%;height:100%;display:block}
.viz figcaption{font-family:var(--mono);font-size:.68rem;letter-spacing:.05em;color:var(--ink-faint);padding:.7rem .95rem;border-top:1px solid var(--line-2);display:flex;justify-content:space-between;gap:1rem;background:rgba(0,0,0,.25)}
.viz figcaption .t{color:var(--lava-2)}
.viz.cold figcaption .t{color:var(--ice)}
.viz.leaf figcaption .t{color:var(--leaf)}
.feature{margin:clamp(3rem,7vh,6rem) 0}
.feature .stage{aspect-ratio:21/9}
@media(max-width:860px){.feature .stage{aspect-ratio:3/2}}
@media(max-width:520px){.feature .stage{aspect-ratio:5/4}}
.feature-cap{font-family:var(--read);font-style:italic;color:var(--ink-dim);font-size:1.02rem;margin-top:1rem;text-align:center;max-width:60ch;margin-inline:auto}

/* concept cards */
.cards{display:grid;grid-template-columns:1fr 1fr;gap:1.4rem;margin:2rem 0}
@media(max-width:640px){.cards{grid-template-columns:1fr}}
.card{border:1px solid var(--line);border-radius:8px;padding:1.6rem 1.5rem;background:linear-gradient(160deg,rgba(255,90,31,.05),transparent 70%)}
.card.red{border-color:rgba(214,58,18,.35)}
.card.blue{border-color:rgba(159,214,232,.28);background:linear-gradient(160deg,rgba(159,214,232,.06),transparent 70%)}
.card h3{font-family:var(--mono);font-size:.74rem;letter-spacing:.16em;text-transform:uppercase;color:var(--lava-2);margin-bottom:.7rem;font-weight:600}
.card.blue h3{color:var(--ice)}
.card p{font-size:.98rem;color:var(--ink-dim);margin:0}
.card .big{font-family:var(--serif);font-size:1.5rem;color:var(--ink);display:block;margin-bottom:.3rem;font-weight:420}
.eq{font-family:var(--mono);font-size:clamp(.95rem,.6rem+1vw,1.35rem);text-align:center;padding:1.4rem;border:1px dashed var(--line);border-radius:8px;margin:1.8rem 0;color:var(--sun);letter-spacing:.02em}
.eq b{color:var(--lava-2)}.eq sub{font-size:.7em}
.pull{font-family:var(--serif);font-style:italic;font-weight:340;font-size:clamp(1.4rem,.9rem+2vw,2.4rem);line-height:1.25;text-align:center;max-width:22ch;margin:clamp(3rem,8vh,6rem) auto;color:var(--sun);text-wrap:balance}
.pull.cold{color:var(--ice-2)}

/* two forces */
.forces{display:grid;grid-template-columns:1fr auto 1fr;gap:1.2rem;align-items:stretch;margin:2rem 0}
@media(max-width:640px){.forces{grid-template-columns:1fr}}
.force{border:1px solid var(--line);border-radius:8px;padding:1.4rem;overflow:hidden}
.force .arrow{font-family:var(--mono);font-size:.7rem;letter-spacing:.12em;opacity:.8}
.force.top{background:linear-gradient(180deg,rgba(255,181,71,.1),transparent)}
.force.bot{background:linear-gradient(0deg,rgba(214,58,18,.12),transparent)}
.force h4{font-family:var(--serif);font-weight:460;font-size:1.2rem;margin:.4rem 0}
.force p{font-size:.92rem;color:var(--ink-dim);margin:0}
.vs{display:grid;place-items:center;font-family:var(--mono);color:var(--ink-faint);font-size:.8rem}

/* timeline */
.tl{margin:3rem 0;border-top:1px solid var(--line);border-bottom:1px solid var(--line);padding:2rem 0}
.tl-track{position:relative;height:64px;margin:1.5rem 0 .5rem}
.tl-line{position:absolute;top:32px;left:0;right:0;height:2px;background:linear-gradient(90deg,var(--lava) 0%,var(--sun) 22%,var(--ember) 46%,var(--ice) 60%,var(--ice) 80%,var(--leaf) 100%)}
.tl-pt{position:absolute;top:32px;transform:translate(-50%,-50%);text-align:center}
.tl-dot{width:11px;height:11px;border-radius:50%;background:var(--ink);border:2px solid var(--void);margin:0 auto;box-shadow:0 0 0 1px var(--line)}
.tl-pt .lab{font-family:var(--mono);font-size:.6rem;color:var(--ink-dim);position:absolute;left:50%;transform:translateX(-50%);white-space:nowrap}
.tl-pt .up{bottom:16px}.tl-pt .dn{top:16px}
.tl-scale{display:flex;justify-content:space-between;font-family:var(--mono);font-size:.62rem;color:var(--ink-faint);letter-spacing:.08em}
@media(max-width:720px){.tl{overflow-x:auto;-webkit-overflow-scrolling:touch}.tl-track,.tl-scale{min-width:600px}.tl::after{content:"↔ faites glisser";display:block;font-family:var(--mono);font-size:.6rem;color:var(--ink-faint);margin-top:.6rem;text-align:center}}
/* master chart scrollable on small screens */
.chart-scroll{overflow-x:auto;-webkit-overflow-scrolling:touch}
.chart-scroll svg{position:static;inset:auto;display:block;width:100%;height:auto}
@media(max-width:720px){.chart-scroll svg{min-width:660px}}

/* svg chart helpers */
.axis{stroke:var(--line);stroke-width:1}
.grid-l{stroke:var(--line-2);stroke-width:1}
.axlab{font-family:var(--mono);font-size:11px;fill:var(--ink-faint)}
.axttl{font-family:var(--mono);font-size:11px;fill:var(--ink-dim);letter-spacing:.05em}
.curve{fill:none;stroke-linecap:round;stroke-linejoin:round}
.note{font-family:var(--read);font-size:13px;font-style:italic}

footer{text-align:center;padding:5rem 6vw 6rem;border-top:1px solid var(--line-2);margin-top:3rem}
footer .fine{font-family:var(--mono);font-size:.66rem;color:var(--ink-faint);margin-top:2rem;line-height:2}

.reveal{opacity:0;transform:translateY(34px);transition:opacity 1s cubic-bezier(.2,.7,.2,1),transform 1s cubic-bezier(.2,.7,.2,1)}
.reveal.in{opacity:1;transform:none}
.draw{stroke-dasharray:var(--len,1200);stroke-dashoffset:var(--len,1200);transition:stroke-dashoffset 2.4s cubic-bezier(.4,0,.2,1)}
.in .draw{stroke-dashoffset:0}
@media(prefers-reduced-motion:reduce){.reveal{opacity:1;transform:none}.draw{stroke-dashoffset:0}*{animation:none!important}}