/* ============================================================
   SIGNAL — AI Body of Knowledge
   A control-room console for the frontier of AI engineering.
   ============================================================ */

:root{
  /* palette */
  --void:#080B14;
  --void-2:#0B1020;
  --panel:#101729;
  --panel-2:#141C33;
  --line:#212B45;
  --line-soft:#1A2238;
  --ink:#E8ECF6;
  --muted:#8A93AD;
  --muted-2:#5E6680;
  --signal:#5BE0C8;   /* live loop */
  --pulse:#7C6BFF;    /* iteration */
  --verified:#FFC857; /* goal met */
  --danger:#FF7A7A;

  /* type */
  --display:'Space Grotesk',system-ui,sans-serif;
  --body:'Manrope',system-ui,sans-serif;
  --mono:'JetBrains Mono',ui-monospace,monospace;

  /* metrics */
  --rail-w:248px;
  --maxw:1180px;
  --r:14px;
  --r-sm:9px;
  --ease:cubic-bezier(.22,.61,.36,1);
}

*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{
  font-family:var(--body);
  background:
    radial-gradient(1200px 700px at 78% -8%, rgba(124,107,255,.13), transparent 60%),
    radial-gradient(900px 600px at -5% 12%, rgba(91,224,200,.09), transparent 55%),
    var(--void);
  color:var(--ink);
  -webkit-font-smoothing:antialiased;
  line-height:1.55;
  min-height:100vh;
}
a{color:inherit;text-decoration:none}
em{font-style:normal;color:var(--signal)}
::selection{background:rgba(124,107,255,.35);color:#fff}

/* film grain / faint grid */
.grain{
  position:fixed;inset:0;z-index:0;pointer-events:none;opacity:.5;
  background-image:
    linear-gradient(rgba(255,255,255,.018) 1px,transparent 1px),
    linear-gradient(90deg,rgba(255,255,255,.018) 1px,transparent 1px);
  background-size:48px 48px;
  mask-image:radial-gradient(circle at 50% 30%,#000 0%,transparent 85%);
}

/* ───────────────── NAV RAIL ───────────────── */
.rail{
  position:fixed;top:0;left:0;bottom:0;width:var(--rail-w);z-index:30;
  display:flex;flex-direction:column;
  padding:26px 20px 20px;
  background:linear-gradient(180deg,var(--void-2),rgba(8,11,20,.7));
  border-right:1px solid var(--line-soft);
  backdrop-filter:blur(6px);
}
.brand{display:flex;align-items:center;gap:11px;color:var(--signal)}
.brand__mark{width:34px;height:34px;flex-shrink:0}
.brand__node{fill:var(--verified);transform-origin:20px 20px;animation:brandspin 6s linear infinite}
@keyframes brandspin{to{transform:rotate(360deg)}}
.brand__word{font-family:var(--display);font-weight:700;font-size:1.32rem;letter-spacing:.16em;color:var(--ink)}
.rail__tag{font-family:var(--mono);font-size:.66rem;letter-spacing:.22em;text-transform:uppercase;color:var(--muted);margin:10px 0 26px 1px}

.nav{display:flex;flex-direction:column;gap:2px;overflow-y:auto;flex:1;margin:0 -8px;padding:0 8px}
.nav__item{
  display:flex;align-items:center;gap:10px;
  padding:9px 11px;border-radius:var(--r-sm);
  font-size:.86rem;font-weight:500;color:var(--muted);
  cursor:pointer;border:1px solid transparent;
  transition:background .18s,color .18s,border-color .18s;
  text-align:left;width:100%;background:none;font-family:var(--body);
}
.nav__item:hover{color:var(--ink);background:rgba(255,255,255,.03)}
.nav__item.is-active{color:var(--ink);background:var(--panel);border-color:var(--line)}
.nav__item.is-active .nav__dot{background:var(--signal);box-shadow:0 0 10px var(--signal)}
.nav__dot{width:7px;height:7px;border-radius:50%;background:var(--line);flex-shrink:0;transition:.18s}
.nav__label{flex:1}
.nav__n{font-family:var(--mono);font-size:.7rem;color:var(--muted)}

.rail__foot{margin-top:18px;padding-top:18px;border-top:1px solid var(--line-soft)}
.rail__meta{font-family:var(--mono);font-size:.66rem;color:var(--muted);text-align:center}

/* mobile top bar */
.topbar{display:none}

/* ───────────────── STAGE ───────────────── */
.stage{
  position:relative;z-index:1;
  margin-left:var(--rail-w);
  padding:42px clamp(20px,5vw,64px) 60px;
  max-width:calc(var(--maxw) + var(--rail-w));
}

/* HERO */
.hero{
  display:grid;grid-template-columns:1.25fr .9fr;gap:48px;align-items:center;
  padding:24px 0 54px;
}
.eyebrow{font-family:var(--mono);font-size:.72rem;letter-spacing:.24em;text-transform:uppercase;color:var(--signal);margin-bottom:20px}
.hero__title{
  font-family:var(--display);font-weight:700;letter-spacing:-.02em;line-height:1.02;
  font-size:clamp(2.4rem,5.4vw,4rem);
}
.grad{background:linear-gradient(100deg,var(--signal),var(--pulse));-webkit-background-clip:text;background-clip:text;color:transparent}
.hero__lede{color:var(--muted);max-width:46ch;margin:22px 0 30px;font-size:1.04rem}
.hero__cta{display:flex;gap:14px;flex-wrap:wrap}
.btn{
  display:inline-flex;align-items:center;padding:12px 22px;border-radius:var(--r-sm);
  font-family:var(--mono);font-size:.78rem;letter-spacing:.06em;text-transform:uppercase;font-weight:500;
  cursor:pointer;transition:.18s;border:1px solid transparent;
}
.btn--solid{background:var(--signal);color:#04130F;font-weight:600}
.btn--solid:hover{box-shadow:0 0 26px rgba(91,224,200,.4);transform:translateY(-1px)}
.btn--wire{border-color:var(--line);color:var(--ink)}
.btn--wire:hover{border-color:var(--pulse);color:#fff;box-shadow:0 0 22px rgba(124,107,255,.25)}

/* ORBIT signature */
.orbit{position:relative;display:grid;place-items:center;aspect-ratio:1;max-width:360px;justify-self:center;width:100%}
.orbit__svg{width:100%;height:auto;overflow:visible}
.orbit__track{fill:none;stroke:var(--line);stroke-width:1.5}
.orbit__ring{fill:none;stroke:url(#ring);stroke-width:2.5;stroke-dasharray:741;stroke-dashoffset:741;
  transform:rotate(-90deg);transform-origin:160px 160px;
  animation:trace 7s var(--ease) infinite;filter:drop-shadow(0 0 6px rgba(91,224,200,.4))}
@keyframes trace{
  0%{stroke-dashoffset:741}
  55%{stroke-dashoffset:0;stroke:url(#ring)}
  70%{stroke:var(--verified);filter:drop-shadow(0 0 12px rgba(255,200,87,.7))}
  100%{stroke-dashoffset:0;stroke:var(--verified);opacity:.9}
}
.orbit__stations circle{fill:var(--void);stroke:var(--line);stroke-width:2}
.orbit__pulse{fill:var(--signal);filter:drop-shadow(0 0 9px var(--signal));
  offset-path:path('M 160 42 A 118 118 0 1 1 159.9 42');
  animation:travel 7s var(--ease) infinite}
@keyframes travel{0%{offset-distance:0%}55%,100%{offset-distance:100%}}
.orbit__labels{position:absolute;inset:0;pointer-events:none}
.orbit__labels span{
  position:absolute;font-family:var(--mono);font-size:.62rem;letter-spacing:.16em;text-transform:uppercase;color:var(--muted);
}
.orbit__labels span:nth-child(1){top:-6px;left:50%;transform:translateX(-50%)}
.orbit__labels span:nth-child(2){top:50%;right:-6px;transform:translateY(-50%)}
.orbit__labels span:nth-child(3){bottom:-6px;left:50%;transform:translateX(-50%)}
.orbit__labels span:nth-child(4){top:50%;left:-6px;transform:translateY(-50%)}
.orbit__core{position:absolute;display:grid;place-items:center;text-align:center}
.orbit__core-k{font-family:var(--mono);font-size:.66rem;letter-spacing:.3em;color:var(--muted)}
.orbit__core-v{font-family:var(--display);font-weight:600;font-size:1.1rem;color:var(--signal);transition:color .4s}
.orbit__core-v.is-verified{color:var(--verified)}

/* ───────────────── CONTROLS ───────────────── */
.controls{display:flex;flex-direction:column;gap:16px;margin-bottom:26px}
.search{position:relative;display:flex;align-items:center}
.search__icon{position:absolute;left:16px;width:18px;height:18px;color:var(--muted)}
#search{
  width:100%;padding:14px 16px 14px 46px;border-radius:var(--r);
  background:var(--panel);border:1px solid var(--line);color:var(--ink);
  font-family:var(--body);font-size:.98rem;transition:.18s;
}
#search::placeholder{color:var(--muted)}
#search:focus{outline:none;border-color:var(--signal);box-shadow:0 0 0 3px rgba(91,224,200,.12)}
.search__kbd{position:absolute;right:14px;font-family:var(--mono);font-size:.72rem;color:var(--muted);
  border:1px solid var(--line);border-radius:5px;padding:2px 7px;background:var(--void-2)}

.filterset{display:flex;flex-wrap:wrap;gap:18px}
.chips{display:flex;flex-wrap:wrap;gap:8px}
.chip{
  font-family:var(--mono);font-size:.72rem;letter-spacing:.04em;
  padding:7px 13px;border-radius:100px;cursor:pointer;
  background:transparent;border:1px solid var(--line);color:var(--muted);
  transition:.16s;text-transform:capitalize;
}
.chip:hover{color:var(--ink);border-color:var(--muted)}
.chip.is-on{color:var(--void);background:var(--ink);border-color:var(--ink);font-weight:600}
.chip[data-group="type"].is-on{background:var(--signal);border-color:var(--signal)}
.chip[data-group="level"].is-on{background:var(--pulse);border-color:var(--pulse);color:#fff}

/* result bar */
.resultbar{display:flex;align-items:baseline;gap:14px;margin-bottom:20px;flex-wrap:wrap}
.resultbar__title{font-family:var(--display);font-weight:600;font-size:1.5rem;letter-spacing:-.01em}
.resultbar__count{font-family:var(--mono);font-size:.78rem;color:var(--muted)}
.clearbtn{margin-left:auto;font-family:var(--mono);font-size:.72rem;color:var(--danger);
  background:none;border:none;cursor:pointer;letter-spacing:.04em}
.clearbtn:hover{text-decoration:underline}

/* ───────────────── GRID + CARDS ───────────────── */
.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(290px,1fr));gap:16px}
.card{
  position:relative;display:flex;flex-direction:column;gap:12px;
  padding:22px 20px 20px;border-radius:var(--r);cursor:pointer;
  background:linear-gradient(180deg,var(--panel),var(--void-2));
  border:1px solid var(--line);overflow:hidden;
  transition:transform .2s var(--ease),border-color .2s,box-shadow .2s;
  animation:rise .5s var(--ease) both;
}
@keyframes rise{from{opacity:0;transform:translateY(10px)}to{opacity:1;transform:none}}
.card::before{content:"";position:absolute;inset:0 0 auto 0;height:2px;
  background:linear-gradient(90deg,var(--signal),var(--pulse));opacity:0;transition:.2s}
.card:hover{transform:translateY(-4px);border-color:var(--line);box-shadow:0 18px 40px -22px rgba(0,0,0,.9)}
.card:hover::before{opacity:1}
.card:focus-visible{outline:2px solid var(--signal);outline-offset:2px}
.card__top{display:flex;align-items:center;justify-content:space-between;gap:8px}
.card__type{font-family:var(--mono);font-size:.64rem;letter-spacing:.14em;text-transform:uppercase;color:var(--signal)}
.card__level{font-family:var(--mono);font-size:.62rem;color:var(--muted);border:1px solid var(--line);border-radius:100px;padding:2px 9px}
.card__title{font-family:var(--display);font-weight:600;font-size:1.18rem;line-height:1.22;letter-spacing:-.01em}
.card__sum{color:var(--muted);font-size:.9rem;flex:1}
.card__tags{display:flex;flex-wrap:wrap;gap:6px}
.tag{font-family:var(--mono);font-size:.64rem;color:var(--muted);background:var(--void);border:1px solid var(--line-soft);border-radius:5px;padding:2px 7px}
.card__foot{display:flex;align-items:center;gap:8px;font-family:var(--mono);font-size:.64rem;color:var(--muted)}
.card__src{margin-left:auto;display:inline-flex;align-items:center;gap:5px}
.dot-v{width:6px;height:6px;border-radius:50%;background:var(--verified);box-shadow:0 0 7px var(--verified)}

.empty{grid-column:1/-1;text-align:center;padding:70px 20px;color:var(--muted)}
.empty__big{font-family:var(--display);font-size:1.3rem;color:var(--ink);margin-bottom:8px}

.sitefoot{margin-top:54px;padding-top:22px;border-top:1px solid var(--line-soft);
  display:flex;gap:12px;flex-wrap:wrap;font-family:var(--mono);font-size:.7rem;color:var(--muted)}
.sitefoot__dot{color:var(--line)}

/* ───────────────── DRAWERS ───────────────── */
.scrim{position:fixed;inset:0;z-index:40;background:rgba(4,6,12,.66);backdrop-filter:blur(3px);animation:fade .2s}
@keyframes fade{from{opacity:0}to{opacity:1}}
.drawer{
  position:fixed;top:0;right:0;bottom:0;z-index:50;width:min(640px,94vw);
  background:linear-gradient(180deg,var(--void-2),var(--void));
  border-left:1px solid var(--line);
  transform:translateX(102%);transition:transform .34s var(--ease);
  display:flex;flex-direction:column;
}
.drawer.is-open{transform:none}
.drawer__head{display:flex;align-items:center;justify-content:space-between;
  padding:18px 26px;border-bottom:1px solid var(--line-soft);flex-shrink:0}
.drawer__h{font-family:var(--display);font-weight:600;font-size:1.15rem}
.drawer__body{overflow-y:auto;padding:30px 36px 60px;flex:1}
.iconbtn{background:var(--panel);border:1px solid var(--line);color:var(--ink);
  width:36px;height:36px;border-radius:9px;cursor:pointer;font-size:1rem;transition:.16s}
.iconbtn:hover{border-color:var(--signal);color:var(--signal)}
.iconbtn--close{font-size:.95rem}

/* detail content */
.dt__type{font-family:var(--mono);font-size:.7rem;letter-spacing:.16em;text-transform:uppercase;color:var(--signal);margin-bottom:14px}
.dt__title{font-family:var(--display);font-weight:700;font-size:2rem;line-height:1.1;letter-spacing:-.02em;margin-bottom:14px}
.dt__meta{display:flex;flex-wrap:wrap;gap:8px;margin-bottom:26px}
.dt__pill{font-family:var(--mono);font-size:.66rem;color:var(--muted);border:1px solid var(--line);border-radius:100px;padding:4px 11px}
.dt__pill--lv{color:var(--pulse);border-color:rgba(124,107,255,.4)}
.dt__body{color:#C9D0E2;font-size:1.0rem;line-height:1.7}
.dt__body p{margin:0 0 16px}
.dt__body h4{font-family:var(--display);color:var(--ink);font-size:1.05rem;margin:26px 0 10px}
.dt__body ul{margin:0 0 16px;padding-left:20px}
.dt__body li{margin-bottom:7px}
.dt__body strong{color:var(--ink)}
.dt__body code{font-family:var(--mono);font-size:.86em;background:var(--panel);border:1px solid var(--line-soft);border-radius:5px;padding:1px 6px;color:var(--signal)}
.dt__quote{border-left:3px solid var(--signal);padding:6px 0 6px 18px;margin:0 0 18px;color:var(--ink);font-size:1.08rem;font-style:italic}
.dt__quote cite{display:block;margin-top:8px;font-style:normal;font-family:var(--mono);font-size:.72rem;color:var(--muted)}

.dt__sources{margin-top:34px;padding-top:24px;border-top:1px solid var(--line-soft)}
.dt__sources h4{font-family:var(--mono);font-size:.74rem;letter-spacing:.16em;text-transform:uppercase;color:var(--muted);margin-bottom:14px}
.src{display:flex;align-items:flex-start;gap:11px;padding:11px 0;border-bottom:1px solid var(--line-soft)}
.src:last-child{border-bottom:none}
.src__badge{flex-shrink:0;font-family:var(--mono);font-size:.6rem;letter-spacing:.06em;text-transform:uppercase;
  padding:3px 8px;border-radius:5px;margin-top:2px}
.src__badge--verified{color:var(--verified);background:rgba(255,200,87,.1);border:1px solid rgba(255,200,87,.35)}
.src__badge--cross{color:var(--signal);background:rgba(91,224,200,.1);border:1px solid rgba(91,224,200,.35)}
.src__badge--pending{color:var(--muted);background:var(--panel);border:1px solid var(--line)}
.src__badge--unverified{color:var(--danger);background:rgba(255,122,122,.08);border:1px solid rgba(255,122,122,.3)}
.src__link{font-size:.9rem;color:var(--ink);word-break:break-word}
.src__link:hover{color:var(--signal);text-decoration:underline}
.src__url{display:block;font-family:var(--mono);font-size:.68rem;color:var(--muted);word-break:break-all;margin-top:2px}

/* related */
.dt__related{margin-top:30px}
.dt__related h4{font-family:var(--mono);font-size:.74rem;letter-spacing:.16em;text-transform:uppercase;color:var(--muted);margin-bottom:12px}
.relchip{display:inline-block;font-family:var(--body);font-size:.84rem;color:var(--ink);
  border:1px solid var(--line);border-radius:100px;padding:6px 13px;margin:0 7px 7px 0;cursor:pointer;transition:.16s}
.relchip:hover{border-color:var(--signal);color:var(--signal)}

/* ───────────────── RESPONSIVE ───────────────── */
@media (max-width:880px){
  .rail{transform:translateX(-100%);transition:transform .3s var(--ease);box-shadow:0 0 50px rgba(0,0,0,.6)}
  .rail.is-open{transform:none}
  .topbar{display:flex;position:sticky;top:0;z-index:25;align-items:center;justify-content:space-between;
    padding:12px 16px;background:rgba(8,11,20,.92);backdrop-filter:blur(8px);border-bottom:1px solid var(--line-soft)}
  .topbar__brand{font-family:var(--display);font-weight:700;letter-spacing:.16em;color:var(--ink)}
  .stage{margin-left:0;padding:24px clamp(16px,5vw,28px) 48px}
  .hero{grid-template-columns:1fr;gap:30px;padding-top:6px}
  .orbit{max-width:280px;order:-1}
  .hero__title{font-size:clamp(2rem,9vw,2.8rem)}
}
@media (min-width:881px){.topbar{display:none}}

/* reduced motion */
@media (prefers-reduced-motion:reduce){
  *{animation-duration:.001ms!important;animation-iteration-count:1!important;transition-duration:.01ms!important}
  .orbit__ring{stroke-dashoffset:0;stroke:var(--verified)}
  .orbit__pulse{offset-distance:100%}
}