/* ============================================================
   CORE·LAB — shared core stylesheet
   Design tokens + base + site-wide topbar. Linked by every page.
   Page-specific styles stay in each page's own <style> block.
   ============================================================ */

:root{
  /* surfaces */
  --bg:#090c11; --panel:#0f141c; --panel-2:#141b25; --panel-3:#0c1118;
  --line:#1d2735; --line-bright:#2e3e52;
  /* ink */
  --ink:#c4d2e0; --ink-dim:#7d8da0; --ink-faint:#4c5a6c; --white:#eef4fa;
  /* accents (shared vocabulary across the site) */
  --amber:#e8a13a;   /* core / call control */
  --cyan:#3fb6d8;    /* transport / system / network */
  --green:#43d17a;   /* field / RF / pass */
  --violet:#9b7bd4;  /* dispatch */
  --fault:#e8604f;   /* fault / fail */
  --steel:#7d8da0;   /* foundations */
  --lock:#3a4658;
  /* diagram node fills — the interior of an SVG box, tinted toward its stroke accent.
     Hand-picked, NOT alpha blends of the accents: no color-mix() reproduces them.
     Do not "simplify" these into a blend; that is a restyle, not a refactor. */
  --node-fill-cyan:#0b1820;
  --node-fill-amber:#1a130a;
  --node-fill-green:#0c1810;
  --node-fill-violet:#15101f;
  /* tier colors */
  --t0:var(--steel); --t1:var(--green); --t2:var(--cyan); --t3:var(--amber);
  /* type */
  --mono:"SFMono-Regular",ui-monospace,"Cascadia Mono","JetBrains Mono",Menlo,Consolas,monospace;
  --sans:"Inter","Segoe UI",system-ui,-apple-system,sans-serif;
}

*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{
  background:var(--bg);color:var(--ink);font-family:var(--sans);line-height:1.55;
  -webkit-font-smoothing:antialiased;min-height:100vh;
}
@media (prefers-reduced-motion:reduce){*{animation-duration:.001ms!important;transition:none!important;scroll-behavior:auto!important}}
a{color:inherit}
:focus-visible{outline:2px solid var(--cyan);outline-offset:2px}

/* ---------- site-wide topbar (rendered by nav.js) ---------- */
.cl-topbar{position:sticky;top:0;z-index:80;background:rgba(9,12,17,.93);backdrop-filter:blur(8px);
  border-bottom:1px solid var(--line);display:flex;align-items:center;gap:13px;padding:10px 20px;font-family:var(--mono)}
.cl-topbar .cl-dot{width:9px;height:9px;border-radius:50%;background:var(--green);box-shadow:0 0 8px var(--green);animation:cl-pulse 2.4s infinite;flex-shrink:0}
@keyframes cl-pulse{0%,100%{opacity:1}50%{opacity:.35}}
.cl-topbar .cl-brand{font-weight:700;letter-spacing:.18em;color:var(--white);font-size:.8rem;text-decoration:none;white-space:nowrap}
.cl-topbar .cl-brand span{color:var(--cyan)}
.cl-topbar .cl-tag{font-size:.6rem;color:var(--ink-faint);letter-spacing:.1em;text-transform:uppercase;white-space:nowrap}
.cl-nav{margin-left:auto;display:flex;align-items:center;gap:4px}
.cl-nav a{font-size:.62rem;color:var(--ink-dim);letter-spacing:.07em;text-transform:uppercase;text-decoration:none;
  padding:6px 10px;border-radius:6px;transition:.14s;white-space:nowrap}
.cl-nav a:hover{color:var(--white);background:rgba(255,255,255,.04)}
.cl-nav a.active{color:var(--cyan)}
.cl-nav a.ext::after{content:"↗";font-size:.7em;margin-left:3px;opacity:.6}
.cl-nav .cl-sep{width:1px;height:16px;background:var(--line-bright);margin:0 4px}

/* dropdown groups */
.cl-group{position:relative}
.cl-grp-btn{font-family:inherit;font-size:.62rem;color:var(--ink-dim);letter-spacing:.07em;text-transform:uppercase;
  background:none;border:none;cursor:pointer;padding:6px 10px;border-radius:6px;transition:.14s;white-space:nowrap;display:flex;align-items:center;gap:5px}
.cl-grp-btn:hover{color:var(--white);background:rgba(255,255,255,.04)}
.cl-grp-btn.active{color:var(--cyan)}
.cl-caret{font-size:.7em;opacity:.6;transition:transform .15s}
.cl-group.open .cl-caret{transform:rotate(180deg)}
.cl-menu{position:absolute;top:100%;right:0;margin-top:6px;background:var(--panel);border:1px solid var(--line);border-radius:8px;
  padding:6px;min-width:200px;display:none;flex-direction:column;gap:2px;box-shadow:0 8px 24px rgba(0,0,0,.4);z-index:90}
.cl-group:hover .cl-menu,.cl-group.open .cl-menu{display:flex}
.cl-menu a{font-size:.64rem;padding:9px 11px;border-radius:6px;text-transform:none;letter-spacing:.02em;color:var(--ink-dim)}
.cl-menu a:hover{color:var(--white);background:rgba(255,255,255,.05)}
.cl-menu a.active{color:var(--cyan);background:rgba(63,182,216,.08)}

/* hamburger for narrow screens */
.cl-burger{display:none;margin-left:auto;background:none;border:1px solid var(--line-bright);border-radius:6px;
  color:var(--ink-dim);font-family:var(--mono);font-size:.7rem;padding:6px 10px;cursor:pointer}
.cl-burger:hover{color:var(--cyan);border-color:var(--cyan)}
@media (max-width:860px){
  .cl-nav{display:none;position:absolute;top:100%;left:0;right:0;background:var(--panel);border-bottom:1px solid var(--line);
    flex-direction:column;align-items:stretch;gap:0;padding:6px}
  .cl-nav.open{display:flex}
  .cl-nav a{padding:11px 14px;border-radius:0}
  .cl-nav .cl-sep{display:none}
  /* groups become inline stacked sections on mobile */
  .cl-group{position:static}
  .cl-grp-btn{width:100%;justify-content:space-between;padding:11px 14px;border-radius:0;border-top:1px solid var(--line)}
  .cl-menu{position:static;display:none;border:none;box-shadow:none;background:var(--panel-2);margin:0;border-radius:0;padding:0 0 0 10px;min-width:0}
  .cl-group:hover .cl-menu{display:none}
  .cl-group.open .cl-menu{display:flex}
  .cl-burger{display:block}
}


/* ---------- glossary tooltips (shared) ---------- */
/* term text stays plain; the ⓘ button is the affordance */
.cl-term{color:inherit}
.cl-info{display:inline-flex;align-items:center;justify-content:center;vertical-align:baseline;
  width:1.05em;height:1.05em;margin:0 .12em 0 .18em;padding:0;border:none;background:none;
  color:var(--cyan);font-size:.82em;line-height:1;cursor:pointer;border-radius:50%;
  transition:color .14s,background .14s,transform .14s;position:relative;top:.02em}
.cl-info:hover,.cl-info:focus{color:var(--white);background:rgba(63,182,216,.22);outline:none;transform:translateY(-1px)}
.cl-info:focus-visible{box-shadow:0 0 0 2px var(--cyan)}
.cl-tip{position:fixed;z-index:200;transform:translate(-50%,-100%);background:var(--panel);color:var(--ink);
  border:1px solid var(--cyan);border-radius:8px;padding:11px 13px 10px;font-family:var(--sans);font-size:.8rem;line-height:1.45;
  box-shadow:0 8px 28px rgba(0,0,0,.5);opacity:0;transition:opacity .15s;max-width:300px;pointer-events:none}
.cl-tip.show{opacity:1;pointer-events:auto}
.cl-tip.below{transform:translate(-50%,0)}
.cl-tip .cl-tip-body{color:var(--ink)}
.cl-tip .cl-tip-more{display:inline-block;margin-top:8px;font-family:var(--mono);font-size:.64rem;letter-spacing:.04em;
  color:var(--cyan);text-decoration:none;border-top:1px solid var(--line);padding-top:7px;width:100%}
.cl-tip .cl-tip-more:hover{color:var(--white)}
.cl-tip::after{content:"";position:absolute;left:50%;bottom:-6px;transform:translateX(-50%);
  border:6px solid transparent;border-top-color:var(--cyan);border-bottom:0}
.cl-tip.below::after{bottom:auto;top:-6px;border-top:0;border-bottom-color:var(--cyan)}
@media (prefers-reduced-motion:reduce){.cl-tip,.cl-info{transition:none}}

/* ---------- lesson completion component (v1.23.0) ---------- */
.cl-completion-zone{max-width:1080px;margin:18px auto 0;padding:0 20px}
.cl-complete-btn{width:100%;font-family:var(--mono);font-size:.72rem;letter-spacing:.05em;text-transform:uppercase;
  background:var(--panel-3);color:var(--ink);border:1px solid var(--line-bright);border-radius:10px;padding:15px;
  cursor:pointer;transition:background .16s,border-color .16s,color .16s,outline-color .16s,transform .16s}
.cl-complete-btn:hover{border-color:var(--green);color:var(--white)}
/* Enabled-state only: progress.js sets btn.disabled on completion, so a .done button
   never receives focus. Scoping here keeps the ring off dead elements. */
.cl-complete-btn:not(.done):focus-visible{outline:2px solid var(--green);outline-offset:2px;
  border-color:var(--green);color:var(--white)}
.cl-complete-btn:not(.done):active{background:var(--panel-2);border-color:var(--green);
  color:var(--white);transform:translateY(1px)}
.cl-complete-btn.done{background:color-mix(in srgb,var(--green) 10%,transparent);border-color:var(--green);color:var(--green);cursor:default}
@media (prefers-reduced-motion:reduce){.cl-complete-btn{transition:none}}