/* ==========================================================================
   Workbench — shared stylesheet
   Used by: index.html + all subject hub pages (math, physics, biology, ...)
   coding.html keeps its own self-contained stylesheet (legacy, unchanged).
   ========================================================================== */

@import url('https://fonts.googleapis.com/css2?family=Fraunces:ital,opsz,wght@0,9..144,500;0,9..144,600;0,9..144,700;1,9..144,500;1,9..144,600;1,9..144,700&family=Space+Grotesk:wght@500;600;700&family=IBM+Plex+Sans:ital,wght@0,400;0,500;0,600;1,400&family=IBM+Plex+Mono:wght@400;500;600&display=swap');

:root{
  --ink:#101119;
  --panel:#171926;
  --panel-2:#1e2130;
  --panel-3:#262a3c;
  --line:#2f3346;
  --text:#E8E6DD;
  --text-dim:#9A9DB0;
  --text-faint:#666981;
  --amber:#E8A05C;
  --amber-soft:#E8A05C22;
  --blue:#7FB0E0;
  --blue-soft:#7FB0E01f;
  --mauve:#C98FB0;
  --mauve-soft:#C98FB01f;
  --green:#4FBF67;
  --green-soft:#4FBF671c;
  --green-dark:#3da354;
  --red:#E08585;
  --red-soft:#E0858518;
  --sans:'IBM Plex Sans',system-ui,sans-serif;
  --disp:'Fraunces','Space Grotesk',system-ui,serif;
  --disp2:'Space Grotesk',system-ui,sans-serif;
  --mono:'IBM Plex Mono',ui-monospace,monospace;
  --maxw:1160px;
}

*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{
  background:var(--ink);
  color:var(--text);
  font-family:var(--sans);
  font-size:17px;
  line-height:1.65;
  -webkit-font-smoothing:antialiased;
  overflow-x:hidden;
}
body::before{
  content:"";position:fixed;inset:0;pointer-events:none;z-index:0;
  background:
    radial-gradient(900px 500px at 80% -5%, #1c2030 0%, transparent 60%),
    radial-gradient(700px 600px at -10% 30%, #181a28 0%, transparent 55%),
    radial-gradient(640px 460px at 50% 8%, #E8A05C14 0%, transparent 62%);
}
body::after{
  content:"";position:fixed;inset:0;pointer-events:none;z-index:0;
  background-image:radial-gradient(#ffffff20 1px, transparent 1px);
  background-size:26px 26px;
  background-position:-4px -4px;
}
.wrap{position:relative;z-index:1;max-width:var(--maxw);margin:0 auto;padding:0 28px}
a{color:inherit}
img{max-width:100%;display:block}
::-webkit-scrollbar{width:10px;height:10px}
::-webkit-scrollbar-track{background:var(--ink)}
::-webkit-scrollbar-thumb{background:var(--panel-3);border-radius:20px;border:2px solid var(--ink)}
::-webkit-scrollbar-thumb:hover{background:var(--line)}
*{scrollbar-color:var(--panel-3) var(--ink);scrollbar-width:thin}
::selection{background:var(--amber);color:var(--ink)}
:focus-visible{outline:2px solid var(--amber);outline-offset:3px;border-radius:4px}
@media(prefers-reduced-motion:reduce){*{animation-duration:.01ms!important;transition-duration:.01ms!important;scroll-behavior:auto}}

/* ---------- nav ---------- */
nav{
  position:sticky;top:0;z-index:40;
  backdrop-filter:blur(12px);
  background:#101119cc;border-bottom:1px solid var(--line);
}
.nav-in{max-width:var(--maxw);margin:0 auto;padding:14px 28px;display:flex;align-items:center;gap:16px}
.brand{font-family:var(--mono);font-weight:600;font-size:15px;letter-spacing:.5px;color:var(--text);display:flex;align-items:center;gap:9px;text-decoration:none}
.brand .blip{width:9px;height:9px;border-radius:2px;background:var(--amber);box-shadow:0 0 10px var(--amber);animation:pulse-dot 2.4s ease-in-out infinite;flex-shrink:0}
@keyframes pulse-dot{0%,100%{opacity:.4;transform:scale(.85)}50%{opacity:1;transform:scale(1.15)}}
.nav-links{display:flex;align-items:center;gap:10px;margin-left:auto;flex-wrap:nowrap;justify-content:flex-end}
.nav-group{display:flex;align-items:center;gap:2px;flex-wrap:nowrap;justify-content:flex-end}
.nav-sections a{
  font-family:var(--mono);font-size:12.5px;color:var(--text-faint);text-decoration:none;
  padding:7px 11px;border-radius:7px;transition:.2s;letter-spacing:.2px;white-space:nowrap;
}
.nav-sections a:hover{color:var(--text);background:var(--panel-2)}
.nav-sep{width:1px;height:18px;background:var(--line);flex-shrink:0}
.nav-links a.cta{
  font-family:var(--mono);font-size:12.5px;text-decoration:none;letter-spacing:.3px;
  padding:8px 15px;border-radius:8px;transition:.2s;white-space:nowrap;
  color:var(--mauve);border:1px solid #C98FB040;
}
.nav-links a.cta:hover{background:var(--mauve);color:#1a0f17}
.nav-links a.cta.solid{background:linear-gradient(135deg,var(--green),var(--green-dark));color:#0c1f10;border:none;font-weight:600}
.nav-links a.cta.solid:hover{filter:brightness(1.08);color:#0c1f10}
@media(max-width:980px){.nav-sections,.nav-sep{display:none}}
@media(max-width:480px){.nav-links a.cta:not(.solid){display:none}}

/* ---------- eyebrow / section head ---------- */
.eyebrow{
  font-family:var(--mono);font-size:13px;letter-spacing:3px;text-transform:uppercase;
  color:var(--amber);margin-bottom:22px;display:flex;align-items:center;gap:12px;
}
.eyebrow::before{content:"";width:34px;height:1px;background:var(--amber)}
.eyebrow::after{
  content:"";display:inline-block;width:5px;height:5px;border-radius:50%;
  background:var(--amber);box-shadow:0 0 8px 2px var(--amber);
  animation:pulse-dot 2.4s ease-in-out infinite;
}
.eyebrow.blue{color:var(--blue)}.eyebrow.blue::before{background:var(--blue)}.eyebrow.blue::after{background:var(--blue)}
.eyebrow.mauve{color:var(--mauve)}.eyebrow.mauve::before{background:var(--mauve)}.eyebrow.mauve::after{background:var(--mauve)}

section{padding:86px 0;border-top:1px solid var(--line);position:relative}
h2{font-family:var(--disp);font-weight:600;font-size:clamp(28px,4vw,42px);letter-spacing:-.8px;line-height:1.1}
.sec-sub{color:var(--text-dim);max-width:660px;margin-bottom:42px;font-size:17.5px}

/* ---------- hero ---------- */
header.hero{padding:80px 0 34px;position:relative}
header.hero::before{
  content:"";position:absolute;top:-120px;left:50%;transform:translateX(-46%);
  width:900px;height:520px;pointer-events:none;z-index:-1;
  background:radial-gradient(closest-side, #E8A05C26, #7FB0E014 55%, transparent 75%);
  filter:blur(10px);
}
h1{
  font-family:var(--disp);font-weight:600;line-height:1.05;letter-spacing:-.5px;
  font-size:clamp(44px,7.4vw,80px);margin-bottom:22px;
  font-optical-sizing:auto;
}
h1 .accent{
  font-style:italic;font-family:var(--disp);display:inline-block;padding-right:.12em;margin-right:-.12em;
  background:linear-gradient(100deg, var(--amber) 10%, var(--mauve) 55%, var(--blue) 100%);
  -webkit-background-clip:text;background-clip:text;color:transparent;
}
.type-line{min-height:1.1em;display:inline-block}
.cursor-blink{display:inline-block;width:8px;height:.85em;background:var(--amber);vertical-align:-.1em;animation:blink 1s steps(1) infinite;margin-left:2px}
@keyframes blink{50%{opacity:0}}
.lede{font-size:clamp(18px,2.4vw,22px);color:var(--text-dim);max-width:680px;line-height:1.55}
.lede b{color:var(--text);font-weight:500}
.hero-ctas{display:flex;gap:14px;margin-top:32px;flex-wrap:wrap}

/* ---------- topic search ---------- */
.topic-search-wrap{position:relative;max-width:560px;margin-top:30px}
.topic-search{
  display:flex;align-items:center;gap:12px;background:var(--panel);border:1px solid var(--line);
  border-radius:14px;padding:15px 18px;transition:.2s;
}
.topic-search:focus-within{border-color:var(--amber);box-shadow:0 0 0 3px var(--amber-soft)}
.ts-icon{font-size:18px;color:var(--text-faint);flex-shrink:0}
.topic-search input{
  flex:1;background:none;border:none;outline:none;color:var(--text);
  font-family:var(--sans);font-size:15.5px;
}
.topic-search input::placeholder{color:var(--text-faint)}
.topic-suggestions{
  position:absolute;top:calc(100% + 8px);left:0;right:0;z-index:30;
  background:var(--panel);border:1px solid var(--line);border-radius:14px;overflow:hidden;
  box-shadow:0 24px 48px -20px #000c;
}
.topic-suggestions[hidden]{display:none}
.ts-item{
  display:flex;align-items:center;justify-content:space-between;gap:12px;width:100%;
  padding:13px 18px;background:none;border:none;border-bottom:1px solid var(--line);color:var(--text);
  font-family:var(--sans);font-size:14.5px;text-align:left;cursor:pointer;transition:.15s;
}
.ts-item:last-child{border-bottom:none}
.ts-item:hover{background:var(--panel-2)}
.ts-item .ts-subject{font-family:var(--mono);font-size:11px;color:var(--text-faint);letter-spacing:.3px}
.ts-empty{padding:16px 18px;font-family:var(--mono);font-size:13px;color:var(--text-faint);line-height:1.5}

.btn{
  font-family:var(--mono);font-size:13.5px;font-weight:600;padding:13px 24px;border-radius:10px;cursor:pointer;
  background:linear-gradient(135deg,var(--green),var(--green-dark));color:#0c1f10;border:none;transition:.2s;letter-spacing:.3px;
  box-shadow:0 6px 18px -8px #4FBF6770;text-decoration:none;display:inline-flex;align-items:center;gap:8px;
}
.btn:hover{filter:brightness(1.08);transform:translateY(-1px);box-shadow:0 10px 22px -8px #4FBF6790}
.btn.ghost{background:transparent;border:1px solid var(--line);color:var(--text-dim);box-shadow:none}
.btn.ghost:hover{color:var(--text);border-color:var(--panel-3);transform:none;filter:none}

/* ---------- demo preview cards (hero) ---------- */
.demo-row{display:grid;grid-template-columns:repeat(3,1fr);gap:20px;margin-top:52px;align-items:start}
@media(max-width:900px){.demo-row{grid-template-columns:1fr}}
.demo-card{
  display:flex;flex-direction:column;gap:14px;
}
.demo-card-win{
  background:var(--panel);border:1px solid var(--line);border-radius:14px;overflow:hidden;
  transition:.22s;box-shadow:0 20px 44px -30px #000b;
}
.demo-card:hover .demo-card-win{transform:translateY(-3px);border-color:var(--panel-3);box-shadow:0 26px 54px -28px #000d}
.demo-card-win{transition:.22s}
.dc-bar{
  display:flex;align-items:center;gap:8px;padding:11px 14px;
  background:var(--panel-2);border-bottom:1px solid var(--line);
}
.dc-dot{width:10px;height:10px;border-radius:50%;flex-shrink:0}
.dc-dot.r{background:#E08585}.dc-dot.y{background:#E8A05C}.dc-dot.g{background:#8FBF9F}
.dc-bar-title{font-family:var(--mono);font-size:11.5px;color:var(--text-faint);letter-spacing:.2px;margin-left:6px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.demo-card .dc-stage{
  height:180px;background:var(--panel-2);position:relative;overflow:hidden;
}
.dc-label{
  position:absolute;font-family:var(--mono);font-size:11.5px;color:var(--amber);z-index:2;
  background:#101119b3;padding:3px 8px;border-radius:6px;letter-spacing:.2px;
}
.dc-label-tl{top:10px;left:10px}
.dc-label-tr{top:10px;right:10px;color:var(--text-dim)}
.dc-caption{
  position:absolute;left:0;right:0;bottom:0;padding:9px 12px 8px;z-index:2;
  font-family:var(--mono);font-size:11.5px;color:var(--text-dim);letter-spacing:.2px;
  background:linear-gradient(0deg,#101119e6,transparent);
}
.dc-pill{
  display:inline-flex;align-items:center;gap:9px;align-self:flex-start;
  font-family:var(--sans);font-size:13.5px;color:var(--text-dim);text-decoration:none;
  background:var(--panel);border:1px solid var(--line);border-radius:30px;padding:8px 16px 8px 8px;
  transition:.2s;
}
.dc-pill:hover{color:var(--text);border-color:var(--panel-3);background:var(--panel-2)}
.dc-pill-q{
  width:22px;height:22px;border-radius:50%;background:var(--amber-soft);color:var(--amber);
  display:flex;align-items:center;justify-content:center;font-family:var(--mono);font-size:11px;font-weight:700;flex-shrink:0;
}

/* ---------- topic marquee ---------- */
.lang-marquee{
  margin-top:38px;position:relative;overflow:hidden;
  -webkit-mask-image:linear-gradient(90deg,transparent,#000 8%,#000 92%,transparent);
  mask-image:linear-gradient(90deg,transparent,#000 8%,#000 92%,transparent);
}
.lang-marquee-track{display:flex;gap:10px;width:max-content;animation:marquee 42s linear infinite}
.lang-marquee:hover .lang-marquee-track{animation-play-state:paused}
.lang-marquee.rev .lang-marquee-track{animation-direction:reverse}
.lang-marquee + .lang-marquee{margin-top:12px}
.lang-marquee span{
  font-family:var(--mono);font-size:12.5px;letter-spacing:.3px;color:var(--text-dim);
  border:1px solid var(--line);background:var(--panel);padding:8px 15px;border-radius:20px;
  white-space:nowrap;flex-shrink:0;
}
@keyframes marquee{from{transform:translateX(0)}to{transform:translateX(-50%)}}

/* ---------- how it works ---------- */
.hiw-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:22px;margin-top:36px}
@media(max-width:820px){.hiw-grid{grid-template-columns:1fr}}
.hiw-card{
  background:var(--panel);border:1px solid var(--line);border-radius:16px;padding:28px 26px;
  transition:.2s;position:relative;overflow:hidden;
}
.hiw-card:hover{transform:translateY(-3px);border-color:var(--panel-3);background:var(--panel-2)}
.hiw-step-no{
  font-family:var(--disp);font-weight:700;font-size:15px;color:var(--ink);
  width:34px;height:34px;border-radius:9px;display:flex;align-items:center;justify-content:center;
  margin-bottom:18px;background:var(--hiw,var(--amber));
}
.hiw-card h3{font-family:var(--disp);font-size:19px;font-weight:600;margin-bottom:8px}
.hiw-card p{color:var(--text-dim);font-size:14.5px;line-height:1.55}

/* ---------- interactive demo lab ---------- */
.demo-pick{display:flex;gap:10px;flex-wrap:wrap;margin-bottom:26px}
.demo-pick button{
  font-family:var(--mono);font-size:13px;padding:11px 18px;border-radius:9px;cursor:pointer;
  background:var(--panel);border:1px solid var(--line);color:var(--text-dim);transition:.2s;
}
.demo-pick button:hover{color:var(--text);border-color:var(--panel-3)}
.demo-pick button.active{background:var(--amber);color:#1a1206;border-color:var(--amber);font-weight:600}
.lab{background:var(--panel);border:1px solid var(--line);border-radius:18px;overflow:hidden}
.lab-stage{padding:26px;height:380px;min-height:340px;position:relative}
@media(max-width:640px){.lab-stage{height:320px}}
.lab-controls{display:flex;gap:12px;flex-wrap:wrap;align-items:center;padding:18px 26px;border-top:1px solid var(--line);background:var(--panel-2)}
.lab-controls label{font-family:var(--mono);font-size:12.5px;color:var(--text-dim);display:flex;align-items:center;gap:8px}
.lab-controls input[type=range]{accent-color:var(--amber)}
.lab-controls input[type=number]{
  font-family:var(--mono);font-size:12.5px;color:var(--text);background:var(--panel);
  border:1px solid var(--line);border-radius:6px;padding:3px 6px;
}
.lab-controls input[type=number]:focus{outline:none;border-color:var(--amber)}
.lab-controls select{
  font-family:var(--mono);font-size:12.5px;color:var(--text);background:var(--panel);
  border:1px solid var(--line);border-radius:6px;padding:4px 8px;cursor:pointer;max-width:260px;
}
.lab-controls .spacer{flex:1}
.lab-note{font-family:var(--mono);font-size:12.5px;color:var(--text-faint);padding:12px 26px;border-top:1px solid var(--line)}
canvas{display:block;width:100%;height:100%;border-radius:10px}
.bars-wrap{display:flex;align-items:flex-end;gap:4px;height:280px;width:100%}
.bar{background:linear-gradient(180deg,#f2bb84,var(--amber));border-radius:3px 3px 0 0;flex:1;transition:height .2s ease, background .2s}
.bar.compare{background:linear-gradient(180deg,#fff2d9,#ffcf8f);box-shadow:0 0 12px -2px #E8A05C99}
.bar.sorted{background:linear-gradient(180deg,#a8e0b8,var(--green))}
.dc-label.ok{color:var(--green)}

/* ---------- every subject ---------- */
.subject-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(230px,1fr));gap:16px;margin-top:8px}
.subject-card{
  display:flex;flex-direction:column;gap:10px;text-decoration:none;color:inherit;
  border:1px solid var(--line);border-radius:14px;background:var(--panel);padding:22px;transition:.22s;
}
.subject-card:hover{transform:translateY(-3px);border-color:var(--sc,var(--amber));background:var(--panel-2);box-shadow:0 16px 34px -22px #000c}
.subject-card .sc-icon{font-size:26px}
.subject-card .sc-name{font-family:var(--disp);font-weight:600;font-size:17px}
.subject-card .sc-blurb{color:var(--text-dim);font-size:13.5px;line-height:1.5}
.subject-card .sc-go{font-family:var(--mono);font-size:12px;color:var(--sc,var(--amber));margin-top:2px}

/* ---------- every level ---------- */
.level-tabs{display:flex;gap:8px;flex-wrap:wrap;margin-bottom:24px}
.level-tabs button{
  font-family:var(--disp);font-weight:600;font-size:15.5px;padding:12px 20px;border-radius:11px;cursor:pointer;
  background:var(--panel);border:1px solid var(--line);color:var(--text-dim);transition:.2s cubic-bezier(.2,.7,.3,1);
  display:flex;align-items:center;gap:10px;box-shadow:0 1px 2px rgba(0,0,0,.04);
}
.level-tabs button:hover{color:var(--text);border-color:var(--panel-3);transform:translateY(-1px);box-shadow:0 4px 10px rgba(0,0,0,.08)}
.level-tabs button:active{transform:translateY(0)}
.level-tabs button.active{
  background:var(--panel-2);color:var(--text);border-color:var(--lvl,var(--amber));
  box-shadow:0 0 0 1px var(--lvl,var(--amber)) inset,0 4px 14px -4px var(--lvl,var(--amber));
}
.level-tabs button .lt-dot{width:9px;height:9px;border-radius:3px;background:var(--lvl,var(--amber));transition:transform .2s}
.level-tabs button.active .lt-dot{transform:scale(1.15)}
.level-panel{background:var(--panel);border:1px solid var(--line);border-radius:16px;padding:32px;min-height:200px}
.level-panel .lp-eyebrow{font-family:var(--mono);font-size:12px;letter-spacing:2px;text-transform:uppercase;color:var(--lvl,var(--amber));margin-bottom:12px}
.level-panel h3{font-family:var(--disp);font-size:24px;font-weight:600;margin-bottom:14px;letter-spacing:-.4px}
.level-panel p{color:var(--text-dim);font-size:16px;line-height:1.65;max-width:66ch}
.level-panel .lp-example{
  margin-top:18px;font-family:var(--mono);font-size:13.5px;line-height:1.7;color:var(--text);
  background:#0d0e15;border:1px solid var(--line);border-radius:10px;padding:16px 18px;white-space:pre-wrap;
}

/* ---------- CTA ---------- */
.cta-section{text-align:center;padding:96px 0}
.cta-section h2{margin-bottom:16px}
.cta-section p{color:var(--text-dim);max-width:560px;margin:0 auto 32px;font-size:17px}
.cta-section .hero-ctas{justify-content:center}

/* ---------- footer ---------- */
footer.site-foot{border-top:1px solid var(--line);padding:56px 0 30px}
.foot-grid{display:grid;grid-template-columns:1.4fr 1fr 1fr 1.4fr;gap:32px;margin-bottom:44px}
@media(max-width:760px){.foot-grid{grid-template-columns:1fr 1fr}}
.foot-brand{font-family:var(--mono);font-weight:600;font-size:15px;color:var(--text);display:flex;align-items:center;gap:9px;margin-bottom:10px}
.foot-tag{color:var(--text-faint);font-size:13.5px;max-width:26ch}
.foot-col h4{font-family:var(--mono);font-size:11.5px;letter-spacing:1.5px;text-transform:uppercase;color:var(--text-faint);margin-bottom:14px}
.foot-col a{display:block;font-size:14px;color:var(--text-dim);text-decoration:none;margin-bottom:10px;transition:.15s}
.foot-col a:hover{color:var(--text)}
.foot-bottom{border-top:1px solid var(--line);padding-top:22px;display:flex;justify-content:space-between;align-items:center;flex-wrap:wrap;gap:12px}
.foot-bottom p{font-family:var(--mono);font-size:12.5px;color:var(--text-faint);letter-spacing:.5px}
.foot-legal{display:flex;gap:18px}
.foot-legal a{font-family:var(--mono);font-size:12.5px;color:var(--text-faint);text-decoration:none}
.foot-legal a:hover{color:var(--text-dim)}

/* ---------- subject sub-pages (math.html, physics.html, ...) ---------- */
.spotlight-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:18px;margin-top:8px}
@media(max-width:900px){.spotlight-grid{grid-template-columns:1fr}}
.spotlight{background:var(--panel);border:1px solid var(--line);border-left:3px solid var(--sc,var(--amber));border-radius:14px;padding:24px}
.spotlight h3{font-family:var(--disp);font-size:18px;font-weight:600;margin-bottom:10px;color:var(--text)}
.spotlight p{color:var(--text-dim);font-size:14.5px;line-height:1.6}
.topic-cloud{display:flex;flex-wrap:wrap;gap:10px;margin-top:8px}
.topic-chip{
  font-family:var(--mono);font-size:13px;color:var(--text-dim);background:var(--panel);
  border:1px solid var(--line);padding:9px 16px;border-radius:20px;transition:.18s;
}
.topic-chip:hover{color:var(--text);border-color:var(--sc,var(--amber));background:var(--panel-2)}
.subject-hero-icon{font-size:44px;margin-bottom:18px}
.back-link{
  display:inline-flex;align-items:center;gap:8px;font-family:var(--mono);font-size:13px;color:var(--text-dim);
  text-decoration:none;margin-bottom:28px;padding:8px 14px;border:1px solid var(--line);border-radius:9px;transition:.18s;
}
.back-link:hover{color:var(--text);border-color:var(--panel-3);background:var(--panel-2)}