/* =====================================================================
   AI: Zero → Frontier — knowledge hub (articles + /learn index)
   Server-rendered, dark, cinematic, self-contained. No web fonts, no CDNs.
   Shares the act-accent language of the main site (public/styles.css).
   ===================================================================== */

/* ---------- Accent map: each act owns one accent ---------- */
[data-accent="cold-white"]     { --accent:#eef2f6; --accent-ink:#0a0a0b; }
[data-accent="electric-cyan"]  { --accent:#22d3ee; --accent-ink:#042027; }
[data-accent="deep-blue"]      { --accent:#3b82f6; --accent-ink:#eef2f6; }
[data-accent="spring-green"]   { --accent:#34d399; --accent-ink:#04241a; }
[data-accent="furnace-amber"]  { --accent:#f59e0b; --accent-ink:#2a1a02; }
[data-accent="violet"]         { --accent:#8b5cf6; --accent-ink:#f4f0ff; }
[data-accent="sunset-orange"]  { --accent:#f97316; --accent-ink:#2b1102; }
[data-accent="electric-teal"]  { --accent:#2dd4bf; --accent-ink:#04231f; }
[data-accent="electric-violet"]{ --accent:#a855f7; --accent-ink:#f7f0ff; }
[data-accent="crimson-red"]    { --accent:#ef4444; --accent-ink:#fff0f0; }
[data-accent="molten-gold"]    { --accent:#fbbf24; --accent-ink:#2a1e02; }

:root {
  --bg:#0a0a0b; --bg-1:#0c0d10; --bg-2:#0f1116; --bg-3:#14161d;
  --line:rgba(255,255,255,.08); --line-2:rgba(255,255,255,.14); --line-3:rgba(255,255,255,.22);
  --text:#eef2f6; --muted:#a7b0be; --faint:#6b7482; --dim:#4c545f;
  --r-sm:10px; --r-md:16px; --r-lg:22px; --r-xl:30px;
  --shadow:0 24px 60px -28px rgba(0,0,0,.8);
  --maxw:1180px; --readw:52rem; --gutter:clamp(18px,4vw,44px); --nav-h:60px;
  --sans:ui-sans-serif,system-ui,-apple-system,"Segoe UI",Roboto,Helvetica,Arial,"Apple Color Emoji","Segoe UI Emoji",sans-serif;
  --mono:ui-monospace,"SF Mono","SFMono-Regular",Menlo,Consolas,"Liberation Mono",monospace;
  --ease:cubic-bezier(.22,.61,.36,1);
  --accent:#eef2f6; --accent-ink:#0a0a0b;
  color-scheme:dark; accent-color:var(--accent);
}

*,*::before,*::after{box-sizing:border-box;} *{margin:0;}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth;}
@media (prefers-reduced-motion:reduce){html{scroll-behavior:auto;}}
body{
  font-family:var(--sans); background:var(--bg); color:var(--text);
  line-height:1.6; letter-spacing:.01em; -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility; overflow-x:hidden; min-height:100vh;
}
img,video,svg{max-width:100%;display:block;} a{color:inherit;text-decoration:none;}
button{font:inherit;color:inherit;cursor:pointer;background:none;border:none;} input,select{font:inherit;}
:focus-visible{outline:2px solid color-mix(in srgb,var(--accent) 90%,white);outline-offset:3px;border-radius:6px;}
.skip-link{position:fixed;left:12px;top:-60px;z-index:200;background:var(--bg-3);color:var(--text);padding:10px 16px;border-radius:10px;border:1px solid var(--line-2);transition:top .18s var(--ease);}
.skip-link:focus{top:12px;}
.wrap{width:100%;max-width:var(--maxw);margin-inline:auto;padding-inline:var(--gutter);}

/* ---------- Nav ---------- */
.nav{position:sticky;top:0;z-index:100;backdrop-filter:saturate(140%) blur(14px);-webkit-backdrop-filter:saturate(140%) blur(14px);background:linear-gradient(180deg,rgba(10,10,11,.86),rgba(10,10,11,.55));border-bottom:1px solid var(--line);}
.nav__inner{height:var(--nav-h);display:flex;align-items:center;justify-content:space-between;gap:20px;}
.brand{display:inline-flex;align-items:center;gap:11px;font-weight:650;letter-spacing:.02em;}
.brand__spectrum{width:26px;height:26px;border-radius:8px;flex:none;background:radial-gradient(120% 120% at 30% 30%,#eef2f6 0%,transparent 42%),conic-gradient(from 210deg,#22d3ee,#3b82f6,#8b5cf6,#f97316,#fbbf24,#22d3ee);box-shadow:inset 0 0 0 1px rgba(255,255,255,.16),0 0 22px -6px #3b82f6aa;}
.brand__text{font-size:15px;white-space:nowrap;} .brand__sep,.brand__arrow{color:var(--faint);}
.nav__links{display:flex;align-items:center;gap:clamp(10px,2.4vw,26px);font-size:14px;}
.nav__links a{color:var(--muted);transition:color .16s var(--ease);} .nav__links a:hover{color:var(--text);}
.nav__cta{color:var(--text)!important;font-weight:600;padding:7px 15px;border-radius:999px;border:1px solid var(--line-2);background:color-mix(in srgb,var(--accent) 14%,transparent);}
.nav__cta:hover{border-color:var(--line-3);}
@media (max-width:560px){.nav__links a:not(.nav__cta){display:none;}}

/* ---------- Breadcrumbs ---------- */
.crumbs{font-size:13px;color:var(--muted);padding-top:22px;display:flex;flex-wrap:wrap;gap:6px;align-items:center;}
.crumbs a{color:var(--muted);border-bottom:1px solid transparent;} .crumbs a:hover{color:var(--text);border-color:var(--line-2);}
.crumbs .sep{color:var(--dim);} .crumbs [aria-current]{color:var(--text);}

/* ---------- Article hero ---------- */
.hero{position:relative;padding:26px 0 8px;}
.hero__eyebrow{display:flex;flex-wrap:wrap;gap:10px;align-items:center;font-size:12.5px;color:var(--muted);text-transform:uppercase;letter-spacing:.12em;}
.tag{display:inline-flex;align-items:center;gap:7px;padding:4px 11px;border-radius:999px;border:1px solid color-mix(in srgb,var(--accent) 40%,var(--line-2));background:color-mix(in srgb,var(--accent) 10%,transparent);color:var(--text);letter-spacing:.04em;text-transform:none;font-size:12px;}
.tag__dot{width:8px;height:8px;border-radius:50%;background:var(--accent);box-shadow:0 0 10px -1px var(--accent);}
.hero__title{margin-top:14px;font-size:clamp(1.7rem,4.6vw,2.9rem);line-height:1.08;letter-spacing:-.015em;font-weight:720;}
.hero__summary{margin-top:14px;font-size:clamp(1.02rem,2.2vw,1.22rem);color:var(--muted);max-width:var(--readw);}
.watermark{position:absolute;top:22px;right:var(--gutter);display:inline-flex;align-items:center;gap:8px;opacity:.7;font-size:12px;color:var(--muted);}
.watermark img{width:20px;height:20px;} .watermark b{color:var(--text);font-weight:600;letter-spacing:.02em;}
@media (max-width:640px){.watermark{position:static;margin-top:14px;justify-content:flex-start;}}

/* ---------- Media block ---------- */
.media{margin:22px 0 6px;}
.media__frame{position:relative;aspect-ratio:16/9;border-radius:var(--r-lg);overflow:hidden;border:1px solid var(--line-2);background:radial-gradient(120% 120% at 50% 0,var(--bg-3),var(--bg-1));box-shadow:var(--shadow);}
.media__frame video{width:100%;height:100%;object-fit:cover;background:#000;}
.media__ph{position:absolute;inset:0;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:12px;text-align:center;padding:24px;}
.media__ph img{width:100%;height:100%;object-fit:cover;position:absolute;inset:0;opacity:.28;filter:saturate(.7);}
.media__ph-inner{position:relative;display:flex;flex-direction:column;align-items:center;gap:10px;}
.media__ring{width:52px;height:52px;border-radius:50%;border:2px solid color-mix(in srgb,var(--accent) 60%,var(--line-3));border-top-color:var(--accent);}
.media__ph b{font-weight:640;} .media__ph span{color:var(--muted);font-size:13.5px;max-width:34ch;}
.audio{margin-top:14px;} .audio audio{width:100%;} .audio__label{font-size:12.5px;color:var(--muted);text-transform:uppercase;letter-spacing:.1em;margin-bottom:6px;}

/* ---------- Key points ---------- */
.keypoints{margin:26px 0;border:1px solid var(--line);border-radius:var(--r-md);background:linear-gradient(180deg,var(--bg-1),var(--bg));padding:20px 22px;}
.keypoints h2{font-size:.8rem;text-transform:uppercase;letter-spacing:.14em;color:var(--muted);margin-bottom:12px;}
.keypoints ul{list-style:none;display:grid;gap:11px;}
.keypoints li{position:relative;padding-left:24px;color:var(--text);}
.keypoints li::before{content:"";position:absolute;left:2px;top:.55em;width:9px;height:9px;border-radius:2px;background:var(--accent);box-shadow:0 0 12px -2px var(--accent);}

/* ---------- Article body ---------- */
.article{max-width:var(--readw);margin-inline:auto;}
.prose{font-size:1.06rem;}
.prose h2{margin:34px 0 10px;font-size:1.32rem;letter-spacing:-.01em;font-weight:680;color:var(--text);}
.prose h2::before{content:"";display:inline-block;width:20px;height:2px;background:var(--accent);vertical-align:middle;margin-right:12px;transform:translateY(-4px);}
.prose p{margin:0 0 15px;color:#d8dee7;}
.prose p:first-child{font-size:1.16rem;color:var(--text);}

/* ---------- Transcript ---------- */
.transcript{margin:30px 0;border:1px solid var(--line);border-radius:var(--r-md);overflow:hidden;background:var(--bg-1);}
.transcript>summary{cursor:pointer;list-style:none;padding:16px 20px;display:flex;align-items:center;justify-content:space-between;gap:12px;font-weight:600;}
.transcript>summary::-webkit-details-marker{display:none;}
.transcript>summary::after{content:"▾";color:var(--muted);transition:transform .2s var(--ease);}
.transcript[open]>summary::after{transform:rotate(180deg);}
.transcript>summary span{font-size:12.5px;color:var(--muted);font-weight:500;}
.transcript__body{padding:4px 20px 18px;border-top:1px solid var(--line);}
.transcript__body p{margin:14px 0;color:var(--muted);font-size:.98rem;line-height:1.7;}

/* ---------- Related ---------- */
.related{margin:34px 0;}
.related h2{font-size:.8rem;text-transform:uppercase;letter-spacing:.14em;color:var(--muted);margin-bottom:14px;}
.related__grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(230px,1fr));gap:12px;}
.rcard{display:block;border:1px solid var(--line);border-radius:var(--r-md);padding:14px 16px;background:var(--bg-1);transition:border-color .16s var(--ease),transform .16s var(--ease);}
.rcard:hover{border-color:color-mix(in srgb,var(--accent) 50%,var(--line-3));transform:translateY(-2px);}
.rcard__kicker{font-size:11px;text-transform:uppercase;letter-spacing:.1em;color:var(--accent);}
.rcard__title{margin-top:6px;font-weight:600;font-size:.98rem;line-height:1.35;}

/* ---------- Chips / tags ---------- */
.chips{display:flex;flex-wrap:wrap;gap:8px;margin-top:16px;}
.chip{font-size:12px;color:var(--muted);border:1px solid var(--line-2);border-radius:999px;padding:5px 11px;}
.chip--tag{color:var(--muted);}

/* =====================================================================
   HUB  (/learn)
   ===================================================================== */
.hub-hero{padding:36px 0 8px;}
.hub-hero h1{font-size:clamp(1.9rem,5vw,3rem);letter-spacing:-.02em;font-weight:740;}
.hub-hero p{margin-top:12px;color:var(--muted);max-width:60ch;font-size:1.08rem;}
.tools{position:sticky;top:var(--nav-h);z-index:40;background:linear-gradient(180deg,var(--bg) 60%,transparent);padding:18px 0 12px;}
.searchform{display:flex;flex-wrap:wrap;gap:10px;align-items:center;}
.searchform input[type=search]{flex:1 1 260px;min-width:0;background:var(--bg-2);border:1px solid var(--line-2);border-radius:999px;padding:11px 16px;color:var(--text);}
.searchform select{background:var(--bg-2);border:1px solid var(--line-2);border-radius:999px;padding:11px 14px;color:var(--text);}
.searchform button{background:color-mix(in srgb,var(--accent) 18%,transparent);border:1px solid var(--line-2);border-radius:999px;padding:11px 18px;font-weight:600;color:var(--text);}
.actnav{display:flex;flex-wrap:wrap;gap:8px;margin-top:12px;}
.actnav a{font-size:12.5px;color:var(--muted);border:1px solid var(--line);border-radius:999px;padding:6px 12px;display:inline-flex;align-items:center;gap:7px;}
.actnav a:hover,.actnav a.is-active{color:var(--text);border-color:var(--line-3);}
.actnav a .dot{width:8px;height:8px;border-radius:50%;background:var(--accent);}
.actsec{margin-top:34px;scroll-margin-top:calc(var(--nav-h) + 90px);}
.actsec__head{display:flex;align-items:baseline;gap:12px;border-bottom:1px solid var(--line);padding-bottom:10px;margin-bottom:16px;}
.actsec__code{font-family:var(--mono);font-size:13px;color:var(--accent);}
.actsec__name{font-size:1.3rem;font-weight:680;letter-spacing:-.01em;}
.actsec__count{margin-left:auto;font-size:12.5px;color:var(--faint);}
.cards{display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:14px;}
.card{position:relative;display:flex;flex-direction:column;gap:8px;border:1px solid var(--line);border-radius:var(--r-md);padding:16px 18px;background:linear-gradient(180deg,var(--bg-1),var(--bg));transition:border-color .16s var(--ease),transform .16s var(--ease);overflow:hidden;}
.card::before{content:"";position:absolute;left:0;top:0;bottom:0;width:3px;background:var(--accent);opacity:.85;}
.card:hover{border-color:color-mix(in srgb,var(--accent) 45%,var(--line-3));transform:translateY(-2px);}
.card__top{display:flex;align-items:center;gap:9px;font-size:11.5px;color:var(--muted);}
.card__num{font-family:var(--mono);color:var(--accent);}
.card__kind{border:1px solid var(--line-2);border-radius:999px;padding:2px 8px;text-transform:uppercase;letter-spacing:.08em;font-size:10px;}
.card__title{font-weight:640;font-size:1.02rem;line-height:1.3;}
.card__sum{color:var(--muted);font-size:.9rem;line-height:1.5;}
.card__rt{margin-top:auto;font-size:11.5px;color:var(--faint);font-family:var(--mono);}
.empty{margin-top:40px;color:var(--muted);text-align:center;padding:40px;border:1px dashed var(--line-2);border-radius:var(--r-md);}

/* =====================================================================
   FOOTER — collaboration credit (three logos)
   ===================================================================== */
.footer{margin-top:60px;border-top:1px solid var(--line);background:linear-gradient(180deg,transparent,rgba(255,255,255,.015));}
.footer__inner{padding-block:34px;display:grid;gap:26px;}
.credit{display:flex;flex-direction:column;gap:14px;}
.credit__label{font-size:11.5px;text-transform:uppercase;letter-spacing:.16em;color:var(--faint);}
.credit__row{display:flex;flex-wrap:wrap;align-items:center;gap:clamp(18px,4vw,42px);}
.credit__row a{display:inline-flex;align-items:center;gap:9px;color:var(--muted);transition:color .16s var(--ease),opacity .16s var(--ease);opacity:.9;}
.credit__row a:hover{color:var(--text);opacity:1;}
.credit__logo{height:26px;width:auto;display:block;}
.credit__logo--gv{height:20px;} .credit__name{font-weight:600;letter-spacing:.01em;}
.footer__meta{display:flex;flex-wrap:wrap;justify-content:space-between;gap:12px;font-size:12.5px;color:var(--faint);border-top:1px solid var(--line);padding-top:18px;}
.footer__meta a{color:var(--muted);} .footer__meta a:hover{color:var(--text);}

.main{padding-bottom:20px;}
@media (max-width:560px){.related__grid,.cards{grid-template-columns:1fr;}}