/* Descend — a travel guide to the Abyss.
   ---------------------------------------------------------------------------
   Committed to a single dark look rather than following the viewer's theme: the
   page is a descent into a pit, and a light version of that is a different page.
   Colour does one job here — each layer has a hue, and the hues get colder and
   then hotter as you go down, so a reader knows roughly how deep they are before
   they read the number.
--------------------------------------------------------------------------- */
:root{
  --void:#07080e; --void-2:#0c0e17; --panel:#11131d;
  --ink:#eef1f8; --ink-2:#a7b0c4; --ink-3:#6b7489;
  --hair:rgba(255,255,255,.10); --hair-soft:rgba(255,255,255,.055);
  --gold:#d9a441;
  --sans:-apple-system,BlinkMacSystemFont,"SF Pro Display","Inter","Segoe UI",Roboto,sans-serif;
  --serif:"Iowan Old Style","Palatino Linotype",Palatino,Georgia,serif;
  --mono:ui-monospace,SFMono-Regular,"SF Mono",Menlo,Consolas,monospace;
  color-scheme:dark;
}
*,*::before,*::after{box-sizing:border-box}
html{scroll-behavior:smooth}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}}
body{
  margin:0;background:var(--void);color:var(--ink);font-family:var(--sans);
  font-size:17px;line-height:1.6;letter-spacing:-.01em;
  -webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;
  overflow-x:hidden;
}
img{max-width:100%;display:block}
a{color:inherit;text-decoration:none}
h1,h2,h3{margin:0;font-weight:620;letter-spacing:-.028em;line-height:1.06}
p{margin:0}
ul{margin:0;padding:0;list-style:none}
.wrap{max-width:1080px;margin-inline:auto;padding-inline:clamp(18px,5vw,44px)}
.small{font-size:.84rem;line-height:1.6}

/* ------------------------------------------------------------- top bar --- */
.topbar{
  position:fixed;top:0;left:0;right:0;z-index:60;height:50px;
  display:flex;align-items:center;
  background:linear-gradient(to bottom,rgba(7,8,14,.92),rgba(7,8,14,0));
  -webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);
}
.bar-in{width:100%;max-width:1080px;margin-inline:auto;padding-inline:clamp(18px,5vw,44px);
  display:flex;align-items:center;gap:14px}
.back{color:var(--ink-2);font-size:.88rem;margin-right:auto}
.back:hover{color:var(--ink)}
.depth-live{font-family:var(--mono);font-size:.8rem;color:var(--gold);
  font-variant-numeric:tabular-nums;letter-spacing:.02em}

/* --------------------------------------------------------------- gauge --- */
/* A fixed rail showing how far down the page you are, marked at each layer.
   Hidden on phones, where there is no room to spare. */
.gauge{position:fixed;right:clamp(12px,2.4vw,26px);top:50%;transform:translateY(-50%);
  z-index:50;display:none;height:min(62vh,520px)}
@media(min-width:1080px){.gauge{display:flex;gap:12px;align-items:stretch}}
.gauge-track{width:2px;background:var(--hair);position:relative;border-radius:2px}
.gauge-fill{position:absolute;top:0;left:0;width:100%;height:0;
  background:linear-gradient(to bottom,#6fb3ff,#8f7bd8,#d9a441,#c9603f);border-radius:2px}
.gauge-marks{display:flex;flex-direction:column;justify-content:space-between;
  font-family:var(--mono);font-size:.62rem;color:var(--ink-3);letter-spacing:.04em}
.gauge-marks span{white-space:nowrap;transition:color .3s ease}
.gauge-marks span.on{color:var(--gold)}

/* ---------------------------------------------------------------- hero --- */
.hero{position:relative;min-height:100svh;display:grid;place-items:center;
  padding:90px clamp(18px,5vw,44px) 60px;text-align:center;
  background:
    radial-gradient(115% 78% at 50% -8%, rgba(120,170,255,.16) 0%, transparent 60%),
    radial-gradient(150% 100% at 50% 108%, rgba(217,164,65,.10) 0%, transparent 58%),
    var(--void);
}
.hero-in{max-width:920px;position:relative;z-index:2}
.kicker{font-family:var(--mono);font-size:.74rem;letter-spacing:.2em;text-transform:uppercase;
  color:var(--ink-3);margin-bottom:26px}
.hero h1{font-family:var(--serif);font-weight:500;
  font-size:clamp(2.3rem,7vw,5rem);letter-spacing:-.022em;line-height:1.04}
.sub{margin:26px auto 0;max-width:60ch;color:var(--ink-2);
  font-size:clamp(1rem,1.7vw,1.16rem);line-height:1.65}
.hero-cta{display:flex;gap:12px;justify-content:center;flex-wrap:wrap;margin-top:36px}
.btn{display:inline-flex;align-items:center;padding:12px 26px;border-radius:980px;
  font-size:.95rem;font-weight:500;background:var(--ink);color:var(--void);
  border:1px solid var(--ink);transition:transform .22s cubic-bezier(.2,.7,.2,1),opacity .22s ease}
.btn:hover{transform:translateY(-2px);opacity:.9}
.btn.ghost{background:transparent;color:var(--ink);border-color:var(--hair)}
.btn.ghost:hover{background:rgba(255,255,255,.06);opacity:1}
.scroll-hint{margin-top:46px;color:var(--ink-3);font-size:.84rem;letter-spacing:.02em}
.hero-fade{position:absolute;inset:auto 0 0 0;height:140px;
  background:linear-gradient(to bottom,transparent,var(--void))}

/* --------------------------------------------------------------- terms --- */
.sec-title{font-family:var(--serif);font-weight:500;
  font-size:clamp(1.6rem,3.4vw,2.5rem);letter-spacing:-.02em}
.terms{padding-block:clamp(70px,11vw,130px);background:var(--void-2);
  border-block:1px solid var(--hair-soft)}
.terms-grid{display:grid;gap:22px;margin-top:26px}
@media(min-width:820px){.terms-grid{grid-template-columns:1fr 1fr;gap:34px}}
.terms-grid p{color:var(--ink-2);font-size:1.04rem;line-height:1.7}
.terms-list{margin-top:34px;display:grid;gap:12px}
@media(min-width:820px){.terms-list{grid-template-columns:repeat(3,1fr);gap:18px}}
.terms-list li{border:1px solid var(--hair-soft);border-radius:14px;padding:16px 18px;
  color:var(--ink-2);font-size:.92rem;line-height:1.6;background:var(--panel)}
.terms-list b{color:var(--ink);display:block;margin-bottom:5px;font-weight:600}

/* --------------------------------------------------------------- layer --- */
.layer{position:relative;padding-block:clamp(72px,11vw,132px);
  border-top:1px solid var(--hair-soft);scroll-margin-top:60px;
  background:
    radial-gradient(120% 60% at 50% 0%, color-mix(in srgb, var(--hue) 13%, transparent) 0%, transparent 62%),
    var(--void);
}
.layer-head{display:grid;gap:18px;align-items:start}
@media(min-width:900px){.layer-head{grid-template-columns:210px 1fr;gap:44px}}
.layer-no{font-family:var(--mono);font-size:.72rem;letter-spacing:.18em;text-transform:uppercase;
  color:var(--hue)}
.layer-depth{margin-top:8px;font-family:var(--mono);font-size:.9rem;color:var(--ink-3);
  font-variant-numeric:tabular-nums}
.layer h2{font-family:var(--serif);font-weight:500;
  font-size:clamp(1.85rem,4.6vw,3.1rem);letter-spacing:-.022em}
.layer-blurb{margin-top:16px;color:var(--ink-2);font-size:1.06rem;line-height:1.7;max-width:60ch}

.chips{display:flex;flex-wrap:wrap;gap:8px;margin-top:20px}
.chip{font-size:.76rem;font-family:var(--mono);letter-spacing:.04em;
  border:1px solid var(--hair);border-radius:980px;padding:5px 12px;color:var(--ink-2)}
.chip.grade{border-color:color-mix(in srgb,var(--hue) 55%,transparent);
  color:color-mix(in srgb,var(--hue) 78%, white)}

.cols{display:grid;gap:16px;margin-top:34px}
@media(min-width:760px){.cols{grid-template-columns:1fr 1fr;gap:22px}}
.col{border:1px solid var(--hair-soft);border-radius:18px;padding:22px 24px;background:var(--panel)}
.col h3{font-size:.76rem;letter-spacing:.14em;text-transform:uppercase;color:var(--ink-3);
  font-weight:600;margin-bottom:14px}
.col li{position:relative;padding-left:20px;color:var(--ink-2);font-size:.95rem;
  line-height:1.6;margin-bottom:10px}
.col li:last-child{margin-bottom:0}
.col li::before{content:"";position:absolute;left:3px;top:.66em;width:6px;height:6px;
  border-radius:50%}
.col.charm li::before{background:var(--hue)}
.col.danger li::before{background:#c9603f}
.col.danger h3{color:#c9603f}

.ascent{margin-top:22px;border-left:2px solid color-mix(in srgb,var(--hue) 55%,transparent);
  padding:4px 0 4px 18px}
.ascent .k{font-size:.72rem;letter-spacing:.14em;text-transform:uppercase;color:var(--ink-3);
  display:block;margin-bottom:5px}
.ascent .v{color:var(--ink);font-family:var(--serif);font-size:1.1rem;line-height:1.5}

/* ------------------------------------------------------------- closing --- */
.closing{padding-block:clamp(80px,12vw,150px);text-align:center;
  background:radial-gradient(120% 90% at 50% 100%, rgba(201,96,63,.16) 0%, transparent 62%),var(--void)}
.closing-lede{margin:22px auto 0;max-width:56ch;color:var(--ink-2);font-size:1.06rem;line-height:1.7}
.closing-stats{display:grid;gap:26px;margin-top:clamp(40px,6vw,64px);
  grid-template-columns:repeat(auto-fit,minmax(140px,1fr))}
.closing-stats .n{display:block;font-family:var(--serif);font-size:clamp(1.7rem,4vw,2.6rem);
  letter-spacing:-.02em}
.closing-stats .l{display:block;margin-top:6px;color:var(--ink-3);font-size:.85rem;line-height:1.4}

.foot{border-top:1px solid var(--hair-soft);padding-block:46px 60px;color:var(--ink-3)}
.foot p{max-width:66ch;font-size:.92rem;line-height:1.7}
.foot p+p{margin-top:14px}
.foot a{color:var(--ink-2);border-bottom:1px solid var(--hair)}
.foot a:hover{color:var(--ink)}

/* -------------------------------------------------------------- reveal --- */
.js .rv{opacity:0;transform:translateY(18px)}
.js .rv.in{opacity:1;transform:none;
  transition:opacity .8s cubic-bezier(.2,.7,.2,1),transform .8s cubic-bezier(.2,.7,.2,1)}
@media(prefers-reduced-motion:reduce){
  .js .rv{opacity:1;transform:none}.js .rv.in{transition:none}
  .btn:hover{transform:none}
}