:root {
  --bg: #ecebe3;
  --surface: #f7f6f0;
  --surface-2: #e3e1d7;
  --ink: #11110e;
  --muted: #66655c;
  --line: rgba(17, 17, 14, .14);
  --lime: #d2f53c;
  --on-lime: #11110e;
  --math: #2f41ff;
  --info: #008a76;
  --good: #159947;
  --bad: #e5383b;
  --radius: 22px;
  --display: 'Bricolage Grotesque', 'Segoe UI Variable Display', 'Segoe UI', system-ui, sans-serif;
  --body: 'Geist', 'Segoe UI Variable Text', 'Segoe UI', system-ui, sans-serif;
  --mono: 'Geist Mono', ui-monospace, 'Cascadia Code', Consolas, monospace;
  color-scheme: light;
}
:root[data-theme="dark"] {
  --bg: #0c0c0a;
  --surface: #161613;
  --surface-2: #21211d;
  --ink: #f0eee6;
  --muted: #9b9a8f;
  --line: rgba(240, 238, 230, .14);
  --math: #8c98ff;
  --info: #2dd4b4;
  --good: #3ddc84;
  --bad: #ff6b6e;
  color-scheme: dark;
}

* { box-sizing: border-box; margin: 0; }
html { scroll-behavior: smooth; }
body {
  background: var(--bg); color: var(--ink); font: 16px/1.55 var(--body);
  min-height: 100vh; -webkit-font-smoothing: antialiased; overflow-x: hidden;
}
body::before { /* grain */
  content: ''; position: fixed; inset: 0; pointer-events: none; z-index: 100; opacity: .07; mix-blend-mode: multiply;
  background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='160' height='160'><filter id='n'><feTurbulence type='fractalNoise' baseFrequency='.9' numOctaves='2' stitchTiles='stitch'/></filter><rect width='100%' height='100%' filter='url(%23n)'/></svg>");
}
:root[data-theme="dark"] body::before { mix-blend-mode: screen; opacity: .05; }
a { color: inherit; }
button { font: inherit; color: inherit; cursor: pointer; }
:focus-visible { outline: 2px solid var(--ink); outline-offset: 3px; border-radius: 6px; }
::selection { background: var(--lime); color: var(--on-lime); }
code, .mono { font-family: var(--mono); font-size: .88em; }
.sr { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); }

/* ---------- nav ---------- */
.nav {
  position: fixed; top: 14px; left: 50%; transform: translateX(-50%); z-index: 50;
  display: flex; align-items: center; gap: 4px; padding: 6px;
  background: color-mix(in srgb, var(--surface) 80%, transparent); backdrop-filter: blur(16px) saturate(1.4);
  border: 1px solid var(--line); border-radius: 999px; max-width: calc(100vw - 20px);
  box-shadow: 0 10px 30px -12px rgba(0, 0, 0, .25);
}
.brand { display: flex; align-items: center; gap: 8px; padding: 6px 12px 6px 8px; text-decoration: none; font: 700 15px var(--display); letter-spacing: -.02em; white-space: nowrap; }
.brand i { display: grid; place-items: center; width: 28px; height: 28px; border-radius: 50%; background: var(--ink); color: var(--bg); font: 800 13px var(--mono); font-style: normal; }
.nav-links { display: flex; gap: 2px; overflow-x: auto; scrollbar-width: none; }
.nav-links::-webkit-scrollbar { display: none; }
.nav-links a { padding: 8px 14px; border-radius: 999px; text-decoration: none; font-size: 14px; font-weight: 500; color: var(--muted); white-space: nowrap; transition: .15s; }
.nav-links a:hover { color: var(--ink); background: var(--surface-2); }
.nav-links a[aria-current="page"] { background: var(--ink); color: var(--bg); }
.icon-btn { width: 36px; height: 36px; border-radius: 50%; border: 0; background: transparent; display: grid; place-items: center; flex: none; }
.icon-btn:hover { background: var(--surface-2); }
.lvl { text-decoration: none; display: flex; align-items: center; gap: 6px; padding: 4px 10px; border-radius: 999px; background: var(--lime); color: var(--on-lime); font: 600 12px var(--mono); white-space: nowrap; }

/* ---------- layout ---------- */
main { padding: 96px clamp(16px, 4vw, 48px) 40px; max-width: 1280px; margin: 0 auto; }
.view { display: none; animation: rise .45s cubic-bezier(.2, .7, .2, 1); }
.view.on { display: block; }
@keyframes rise { from { opacity: 0; transform: translateY(14px); } to { opacity: 1; transform: none; } }

.eyebrow { font: 500 12px var(--mono); text-transform: uppercase; letter-spacing: .12em; color: var(--muted); display: inline-flex; align-items: center; gap: 8px; }
.eyebrow::before { content: ''; width: 8px; height: 8px; border-radius: 50%; background: var(--lime); box-shadow: 0 0 0 1px var(--ink); }
h1, h2, h3 { font-family: var(--display); letter-spacing: -.035em; line-height: .95; font-weight: 700; }
.page-h { font-size: clamp(2.6rem, 7vw, 5.5rem); margin: 14px 0 12px; }
.lead { font-size: clamp(1.05rem, 1.6vw, 1.3rem); color: var(--muted); max-width: 60ch; line-height: 1.45; }

.btn {
  display: inline-flex; align-items: center; gap: 10px; padding: 14px 22px; border-radius: 999px;
  border: 1.5px solid var(--ink); background: var(--ink); color: var(--bg); font-weight: 600; text-decoration: none;
  transition: transform .15s, box-shadow .15s, background .15s; line-height: 1;
}
.btn:hover { transform: translate(-2px, -2px); box-shadow: 4px 4px 0 var(--lime), 4px 4px 0 1.5px var(--ink); }
.btn:active { transform: none; box-shadow: none; }
.btn.lime { background: var(--lime); color: var(--on-lime); border-color: var(--on-lime); }
.btn.ghost { background: transparent; color: var(--ink); }
.btn.sm { padding: 9px 14px; font-size: 14px; }
.btn[disabled] { opacity: .4; pointer-events: none; }
.btn svg { width: 16px; height: 16px; }

.card { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: clamp(18px, 2.4vw, 28px); position: relative; overflow: hidden; }
.chip { display: inline-flex; align-items: center; gap: 6px; padding: 5px 11px; border-radius: 999px; border: 1px solid var(--line); font: 500 12px var(--mono); background: var(--surface); }
.chip.mate { color: var(--math); border-color: color-mix(in srgb, var(--math) 40%, transparent); }
.chip.info { color: var(--info); border-color: color-mix(in srgb, var(--info) 40%, transparent); }
.dot { width: 8px; height: 8px; border-radius: 50%; background: currentColor; display: inline-block; }

/* ---------- hero ---------- */
.hero { padding-top: 20px; }
.hero h1 { font-size: clamp(3.6rem, 13.5vw, 11.5rem); line-height: .93; letter-spacing: -.055em; margin: 22px 0 28px; }
.hero h1 span { display: block; }
.hero h1 .hl { display: inline-block; background: var(--lime); color: var(--on-lime); padding: 0 .12em; border-radius: .14em; transform: rotate(-1.5deg); }
.hero h1 .out { color: var(--ink); opacity: .28; }
.hero-row { display: flex; flex-wrap: wrap; gap: 28px 48px; align-items: end; justify-content: space-between; }
.cta { display: flex; flex-wrap: wrap; gap: 12px; }

.ticker { margin: 56px calc(50% - 50vw) 0; overflow: hidden; border-block: 1.5px solid var(--ink); background: var(--ink); color: var(--bg); }
.ticker-track { display: flex; gap: 40px; width: max-content; padding: 14px 0; animation: slide 38s linear infinite; font: 500 17px var(--mono); }
.ticker-track span::after { content: '✦'; margin-left: 40px; color: var(--lime); }
@keyframes slide { to { transform: translateX(-50%); } }

.bento { display: grid; grid-template-columns: repeat(12, 1fr); gap: 14px; margin-top: 56px; }
.bento > * { min-width: 0; }
.b-learn { grid-column: span 7; } .b-ai { grid-column: span 5; } .b-arena { grid-column: span 8; } .b-lab { grid-column: span 4; }
.bento h3 { font-size: clamp(1.8rem, 3.4vw, 2.8rem); margin: 10px 0 10px; }
.bento p { color: var(--muted); max-width: 46ch; }
.bento .go { position: absolute; right: 18px; top: 18px; width: 44px; height: 44px; border-radius: 50%; border: 1.5px solid var(--ink); display: grid; place-items: center; transition: .2s; background: var(--surface); }
.bento a.card { text-decoration: none; display: block; transition: transform .2s, box-shadow .2s; }
.bento a.card:hover { transform: translateY(-4px); }
.bento a.card:hover .go { background: var(--lime); color: var(--on-lime); transform: rotate(-45deg); }
.b-arena { background: var(--ink) !important; color: var(--bg); }
.b-arena p { color: color-mix(in srgb, var(--bg) 65%, transparent); }
.b-arena .go { background: var(--lime); color: var(--on-lime); border-color: var(--lime); }
.b-arena .eyebrow { color: color-mix(in srgb, var(--bg) 65%, transparent); }
.vs { display: grid; grid-template-columns: 1fr auto 1fr; align-items: center; gap: 12px; margin-top: 22px; font-family: var(--display); }
.vs b { font-size: clamp(2.4rem, 5vw, 4rem); letter-spacing: -.05em; line-height: 1; }
.vs small { display: block; font: 500 11px var(--mono); letter-spacing: .1em; text-transform: uppercase; opacity: .6; }
.vs .x { font: 700 13px var(--mono); padding: 8px 12px; border-radius: 999px; background: var(--lime); color: var(--on-lime); }
.vs div:last-child { text-align: right; }
.mini-chat { margin-top: 16px; display: grid; gap: 8px; font-size: 14px; }
.mini-chat div { padding: 10px 14px; border-radius: 16px; max-width: 90%; }
.mini-chat .me { background: var(--ink); color: var(--bg); justify-self: end; border-bottom-right-radius: 4px; }
.mini-chat .ai { background: var(--surface-2); border-bottom-left-radius: 4px; }
.prog { height: 10px; border-radius: 99px; background: var(--surface-2); overflow: hidden; margin-top: 18px; }
.prog > i { display: block; height: 100%; background: var(--ink); border-radius: 99px; transition: width .6s cubic-bezier(.2, .7, .2, 1); }
.big-n { font: 700 clamp(3rem, 7vw, 5.5rem)/1 var(--display); letter-spacing: -.05em; }
.glyphs { position: absolute; right: 22px; bottom: -22px; font: 700 150px/1 var(--display); color: var(--lime); opacity: .9; pointer-events: none; letter-spacing: -.08em; }
.b-learn .glyphs { color: var(--surface-2); }

.steps { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; margin-top: 14px; }
.step { border-top: 1.5px solid var(--ink); padding-top: 14px; }
.step b { font: 600 12px var(--mono); }
.step h4 { font: 700 1.5rem var(--display); letter-spacing: -.03em; margin: 6px 0; }
.step p { color: var(--muted); font-size: 15px; }
.section-h { font-size: clamp(2rem, 4.5vw, 3.4rem); margin: 72px 0 6px; }
footer { padding: 48px clamp(16px, 4vw, 48px) 60px; max-width: 1280px; margin: 40px auto 0; border-top: 1px solid var(--line); display: flex; flex-wrap: wrap; gap: 16px 40px; justify-content: space-between; color: var(--muted); font-size: 14px; }
footer b { color: var(--ink); font-family: var(--display); font-size: 18px; letter-spacing: -.02em; }

/* ---------- learn ---------- */
.filters { display: flex; gap: 8px; margin: 28px 0 20px; flex-wrap: wrap; }
.seg { display: inline-flex; padding: 4px; border-radius: 999px; border: 1px solid var(--line); background: var(--surface); }
.seg button { border: 0; background: transparent; padding: 8px 16px; border-radius: 999px; font-size: 14px; font-weight: 500; color: var(--muted); }
.seg button[aria-pressed="true"], .seg button[aria-selected="true"] { background: var(--ink); color: var(--bg); }
.lessons { display: grid; gap: 10px; }
.lesson { border: 1px solid var(--line); background: var(--surface); border-radius: var(--radius); overflow: hidden; transition: border-color .2s; }
.lesson[open] { border-color: var(--ink); }
.lesson summary { list-style: none; display: grid; grid-template-columns: auto 1fr auto; align-items: center; gap: 18px; padding: 20px 24px; cursor: pointer; }
.lesson summary::-webkit-details-marker { display: none; }
.lesson .num { font: 700 clamp(2rem, 4vw, 3rem) var(--display); letter-spacing: -.05em; color: var(--muted); width: 2.2ch; }
.lesson.mate .num { color: var(--math); } .lesson.info .num { color: var(--info); }
.lesson h3 { font-size: clamp(1.3rem, 2.4vw, 1.9rem); line-height: 1.05; }
.lesson small { color: var(--muted); font-size: 14px; display: block; margin-top: 4px; }
.lesson .tick { width: 32px; height: 32px; border-radius: 50%; border: 1.5px solid var(--line); display: grid; place-items: center; font-size: 14px; }
.lesson.done .tick { background: var(--lime); color: var(--on-lime); border-color: var(--on-lime); }
.lesson-body { padding: 0 24px 24px calc(24px + 2.2ch + 18px); display: grid; gap: 14px; max-width: 86ch; }
.lesson-body p { line-height: 1.65; }
.lesson-body code { background: var(--surface-2); padding: 2px 7px; border-radius: 6px; }
.lesson-body pre { background: var(--ink); color: var(--bg); padding: 18px 20px; border-radius: 14px; overflow-x: auto; font: 14px/1.6 var(--mono); }
.lesson-body pre code { background: none; padding: 0; color: inherit; }
.ex { border-left: 3px solid var(--lime); background: var(--surface-2); padding: 14px 18px; border-radius: 4px 14px 14px 4px; font-family: var(--mono); font-size: 14px; line-height: 1.7; }
.ex span { display: block; font: 600 11px var(--mono); text-transform: uppercase; letter-spacing: .12em; color: var(--muted); margin-bottom: 4px; }
.lesson-actions { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 4px; }

/* ---------- tutor ---------- */
.chat-shell { display: grid; grid-template-columns: 300px 1fr; gap: 14px; margin-top: 28px; align-items: start; }
.chat-side { display: grid; gap: 14px; position: sticky; top: 90px; }
.sugg { display: grid; gap: 8px; }
.sugg button { text-align: left; padding: 11px 14px; border-radius: 14px; border: 1px solid var(--line); background: var(--surface); font-size: 14px; transition: .15s; }
.sugg button:hover { border-color: var(--ink); background: var(--lime); color: var(--on-lime); }
.chat { display: flex; flex-direction: column; height: min(72vh, 720px); min-height: 460px; padding: 0; }
.chat-head { display: flex; justify-content: space-between; align-items: center; padding: 14px 18px; border-bottom: 1px solid var(--line); }
.chat-head .st { display: flex; align-items: center; gap: 8px; font: 500 13px var(--mono); }
.live { width: 9px; height: 9px; border-radius: 50%; background: var(--good); box-shadow: 0 0 0 4px color-mix(in srgb, var(--good) 22%, transparent); }
.msgs { flex: 1; overflow-y: auto; padding: 20px 18px; display: flex; flex-direction: column; gap: 14px; scroll-behavior: smooth; }
.msg { max-width: min(640px, 88%); padding: 12px 16px; border-radius: 20px; line-height: 1.55; font-size: 15.5px; overflow-wrap: anywhere; animation: rise .3s; }
.msg.u { align-self: flex-end; background: var(--ink); color: var(--bg); border-bottom-right-radius: 5px; }
.msg.a { align-self: flex-start; background: var(--surface-2); border-bottom-left-radius: 5px; }
.msg code { background: color-mix(in srgb, var(--ink) 10%, transparent); padding: 1px 6px; border-radius: 5px; }
.msg.u code { background: rgba(255, 255, 255, .15); }
.msg pre { background: var(--ink); color: var(--bg); padding: 12px 14px; border-radius: 12px; overflow-x: auto; margin: 8px 0 2px; font: 13.5px/1.55 var(--mono); }
.msg pre code { background: none; padding: 0; }
.msg ul { padding-left: 20px; margin: 6px 0; }
.msg .src { display: block; margin-top: 8px; font: 500 11px var(--mono); color: var(--muted); text-transform: uppercase; letter-spacing: .08em; }
.typing { display: inline-flex; gap: 4px; padding: 4px 0; }
.typing i { width: 7px; height: 7px; border-radius: 50%; background: var(--muted); animation: blink 1s infinite; }
.typing i:nth-child(2) { animation-delay: .15s; } .typing i:nth-child(3) { animation-delay: .3s; }
@keyframes blink { 0%, 60%, 100% { opacity: .25; transform: none; } 30% { opacity: 1; transform: translateY(-3px); } }
.composer { display: flex; gap: 8px; padding: 12px; border-top: 1px solid var(--line); }
.composer input { flex: 1; min-width: 0; padding: 14px 18px; border-radius: 999px; border: 1px solid var(--line); background: var(--bg); color: var(--ink); font: inherit; }
.composer input:focus { outline: 2px solid var(--ink); }
.settings { display: none; padding: 16px 18px; border-bottom: 1px solid var(--line); background: var(--surface-2); gap: 10px; }
.settings.on { display: grid; }
.field { display: grid; gap: 4px; }
.field label { font: 500 12px var(--mono); color: var(--muted); }
.field input, .field select { padding: 11px 14px; border-radius: 12px; border: 1px solid var(--line); background: var(--bg); color: var(--ink); font: inherit; width: 100%; }
.hint { font-size: 13px; color: var(--muted); }

/* ---------- arena ---------- */
.arena-grid { display: grid; grid-template-columns: 1.25fr 1fr; gap: 14px; margin-top: 28px; align-items: start; }
.setup { display: grid; gap: 22px; }
.setup h4, .board h4 { font: 600 12px var(--mono); text-transform: uppercase; letter-spacing: .12em; color: var(--muted); margin-bottom: 8px; }
.opts { display: flex; flex-wrap: wrap; gap: 8px; }
.opt { padding: 11px 18px; border-radius: 14px; border: 1.5px solid var(--line); background: var(--bg); font-weight: 500; transition: .15s; }
.opt:hover { border-color: var(--ink); }
.opt[aria-pressed="true"] { border-color: var(--ink); background: var(--ink); color: var(--bg); }
.opt small { display: block; font: 400 12px var(--mono); opacity: .65; }
.board table { width: 100%; border-collapse: collapse; font-size: 15px; }
.board th { text-align: left; font: 500 11px var(--mono); text-transform: uppercase; letter-spacing: .1em; color: var(--muted); padding: 6px 8px; }
.board td { padding: 12px 8px; border-top: 1px solid var(--line); }
.board td:first-child { font: 700 18px var(--display); width: 2.2em; }
.board tr:first-child td:first-child { color: var(--math); }
.board td.pts { font-family: var(--mono); font-weight: 600; text-align: right; }
.empty { padding: 28px 8px; color: var(--muted); text-align: center; font-size: 15px; }
.empty b { display: block; font: 700 2.4rem var(--display); color: var(--ink); opacity: .2; margin-bottom: 4px; }

.game { display: none; margin-top: 28px; }
.game.on { display: block; }
.hud { display: grid; grid-template-columns: 1fr auto 1fr; align-items: center; gap: 12px; margin-bottom: 14px; }
.pl { display: flex; align-items: center; gap: 14px; padding: 12px 18px; border-radius: 20px; background: var(--surface); border: 1px solid var(--line); transition: .25s; }
.pl.r { flex-direction: row-reverse; text-align: right; }
.pl.lead-p { border-color: var(--ink); background: var(--lime); color: var(--on-lime); }
.pl .av { width: 44px; height: 44px; border-radius: 50%; display: grid; place-items: center; background: var(--ink); color: var(--bg); font: 700 18px var(--display); flex: none; }
.pl .nm { font: 500 12px var(--mono); text-transform: uppercase; letter-spacing: .06em; opacity: .75; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.pl .sc { font: 700 clamp(1.6rem, 3.4vw, 2.4rem)/1 var(--display); letter-spacing: -.04em; }
.pl .state { font: 500 11px var(--mono); opacity: .7; }
.ring { position: relative; width: 84px; height: 84px; flex: none; }
.ring svg { width: 100%; height: 100%; transform: rotate(-90deg); }
.ring circle { fill: none; stroke-width: 6; }
.ring .bg { stroke: var(--surface-2); }
.ring .fg { stroke: var(--ink); stroke-linecap: round; transition: stroke-dashoffset .1s linear, stroke .3s; }
.ring.low .fg { stroke: var(--bad); }
.ring b { position: absolute; inset: 0; display: grid; place-items: center; font: 700 26px var(--display); }
.qcard { padding: clamp(22px, 4vw, 44px); }
.qmeta { display: flex; justify-content: space-between; gap: 10px; flex-wrap: wrap; margin-bottom: 18px; }
.qtext { font: 600 clamp(1.5rem, 3.2vw, 2.5rem)/1.12 var(--display); letter-spacing: -.03em; white-space: pre-wrap; max-width: 42ch; }
.answers { display: grid; gap: 10px; margin-top: 28px; }
.answers.two { grid-template-columns: 1fr 1fr; gap: 18px; }
.pgrid { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; align-content: start; }
.answers.two .pgrid { grid-template-columns: 1fr; }
.pgrid > h5 { grid-column: 1 / -1; }
#v-arena.playing .page-h, #v-arena.playing .lead, #v-arena.playing > .eyebrow { display: none; }
#v-arena.playing .game { margin-top: 0; }
.pgrid > h5 { font: 600 11px var(--mono); text-transform: uppercase; letter-spacing: .1em; color: var(--muted); }
.ans {
  display: flex; align-items: center; gap: 14px; padding: 16px 18px; border-radius: 16px; border: 1.5px solid var(--line); background: var(--bg);
  text-align: left; font: 500 17px var(--body); transition: transform .12s, border-color .12s, background .12s;
}
.ans:hover:not([disabled]) { border-color: var(--ink); transform: translateY(-2px); }
.ans .k { flex: none; min-width: 28px; height: 28px; padding: 0 6px; border-radius: 8px; border: 1px solid var(--line); display: grid; place-items: center; font: 600 12px var(--mono); color: var(--muted); }
.ans .tags { margin-left: auto; display: flex; gap: 4px; }
.ans .tags i { font: 700 10px var(--mono); font-style: normal; padding: 3px 7px; border-radius: 99px; background: var(--ink); color: var(--bg); }
.ans[disabled] { cursor: default; }
.ans.picked { border-color: var(--ink); background: var(--surface-2); }
.ans.right { background: var(--lime); border-color: var(--on-lime); color: var(--on-lime); }
.ans.right .k { border-color: var(--on-lime); color: var(--on-lime); }
.ans.wrong { border-color: var(--bad); color: var(--bad); background: color-mix(in srgb, var(--bad) 9%, var(--bg)); }
.ans.dim { opacity: .45; }
.reveal { display: none; margin-top: 22px; padding: 18px 20px; border-radius: 16px; background: var(--surface-2); gap: 14px; align-items: center; justify-content: space-between; flex-wrap: wrap; }
.reveal.on { display: flex; animation: rise .3s; }
.reveal p { max-width: 60ch; }
.reveal p b { font-family: var(--mono); font-size: 12px; text-transform: uppercase; letter-spacing: .1em; display: block; color: var(--muted); }
.floatpts { position: fixed; pointer-events: none; font: 800 28px var(--display); color: var(--on-lime); background: var(--lime); padding: 4px 12px; border-radius: 99px; z-index: 60; animation: fly 1s ease-out forwards; }
@keyframes fly { from { opacity: 1; transform: translateY(0) scale(.8); } to { opacity: 0; transform: translateY(-60px) scale(1.1); } }

.result { text-align: center; padding: clamp(28px, 6vw, 64px) 20px; }
.result h2 { font-size: clamp(3rem, 10vw, 8rem); letter-spacing: -.06em; line-height: .85; margin: 16px 0; }
.result .final { display: flex; justify-content: center; gap: 24px; flex-wrap: wrap; margin: 24px 0 8px; }
.result .final div { min-width: 150px; padding: 18px 24px; border-radius: 20px; border: 1px solid var(--line); background: var(--bg); }
.result .final b { display: block; font: 700 3rem/1 var(--display); letter-spacing: -.05em; }
.result .final span { font: 500 12px var(--mono); color: var(--muted); text-transform: uppercase; letter-spacing: .08em; }
.result .win b { background: var(--lime); color: var(--on-lime); padding: 0 .15em; border-radius: 10px; }
.gains { display: flex; gap: 8px; justify-content: center; flex-wrap: wrap; margin: 22px 0; }

/* ---------- lab ---------- */
.lab-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 14px; margin-top: 28px; }
.lab-wide { grid-column: 1 / -1; }
.lab h3 { font-size: 1.8rem; margin-bottom: 4px; }
.plot { width: 100%; aspect-ratio: 16 / 10; border-radius: 16px; background: var(--bg); border: 1px solid var(--line); display: block; margin-top: 14px; }
.sliders { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; margin-top: 18px; }
.sl label { display: flex; justify-content: space-between; font: 500 13px var(--mono); }
.sl output { font-weight: 700; }
input[type=range] { width: 100%; accent-color: var(--ink); height: 28px; }
.readout { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 14px; }
.readout .chip { background: var(--bg); font-size: 13px; padding: 7px 12px; }
.tool-in { display: flex; gap: 8px; margin-top: 14px; flex-wrap: wrap; }
.tool-in input { flex: 1; min-width: 80px; padding: 12px 14px; border-radius: 12px; border: 1px solid var(--line); background: var(--bg); color: var(--ink); font: inherit; }
.tool-out { margin-top: 14px; font: 14px/1.8 var(--mono); background: var(--bg); border: 1px solid var(--line); border-radius: 14px; padding: 14px 16px; min-height: 64px; white-space: pre-wrap; overflow-x: auto; }

/* ---------- profile ---------- */
.prof-grid { display: grid; grid-template-columns: 1fr 1.3fr; gap: 14px; margin-top: 28px; align-items: start; }
.stats { display: grid; grid-template-columns: repeat(2, 1fr); gap: 10px; margin-top: 18px; }
.stat { padding: 16px; border-radius: 16px; background: var(--bg); border: 1px solid var(--line); }
.stat b { display: block; font: 700 2.2rem/1 var(--display); letter-spacing: -.04em; }
.stat span { font: 500 11px var(--mono); text-transform: uppercase; letter-spacing: .08em; color: var(--muted); }
.badges { display: grid; grid-template-columns: repeat(auto-fill, minmax(150px, 1fr)); gap: 10px; margin-top: 14px; }
.badge { padding: 16px; border-radius: 18px; border: 1px dashed var(--line); text-align: center; opacity: .5; filter: grayscale(1); transition: .3s; }
.badge.on { opacity: 1; filter: none; border: 1px solid var(--ink); background: var(--surface); }
.badge i { display: grid; place-items: center; width: 54px; height: 54px; margin: 0 auto 10px; border-radius: 50%; background: var(--lime); color: var(--on-lime); font: 700 22px var(--display); font-style: normal; border: 1.5px solid var(--on-lime); }
.badge:not(.on) i { background: var(--surface-2); color: var(--muted); border-color: var(--line); }
.badge b { display: block; font: 700 15px var(--display); }
.badge small { color: var(--muted); font-size: 12px; line-height: 1.3; display: block; margin-top: 3px; }
.danger { color: var(--bad); border-color: color-mix(in srgb, var(--bad) 50%, transparent); }

.toasts { position: fixed; bottom: 18px; left: 50%; transform: translateX(-50%); z-index: 70; display: grid; gap: 8px; justify-items: center; pointer-events: none; }
.toast { padding: 12px 18px 12px 12px; border-radius: 999px; background: var(--ink); color: var(--bg); display: flex; align-items: center; gap: 12px; font-size: 14px; animation: toast 3.6s forwards; box-shadow: 0 14px 40px -10px rgba(0, 0, 0, .4); }
.toast i { width: 30px; height: 30px; border-radius: 50%; background: var(--lime); color: var(--on-lime); display: grid; place-items: center; font: 700 14px var(--display); font-style: normal; }
@keyframes toast { 0% { opacity: 0; transform: translateY(20px); } 8%, 88% { opacity: 1; transform: none; } 100% { opacity: 0; transform: translateY(10px); } }

/* ---------- responsive ---------- */
@media (max-width: 980px) {
  .b-learn, .b-ai, .b-arena, .b-lab { grid-column: 1 / -1; }
  .chat-shell, .arena-grid, .prof-grid, .lab-grid { grid-template-columns: 1fr; }
  .chat-side { position: static; }
  .steps { grid-template-columns: 1fr; }
}
@media (max-width: 680px) {
  .brand span, .lvl em { display: none; }
  .nav-links a { padding: 8px 10px; font-size: 13px; }
  .hud { grid-template-columns: 1fr 1fr; }
  .hud .ring { grid-column: 1 / -1; grid-row: 1; justify-self: center; }
  .answers.two, .pgrid { grid-template-columns: 1fr; }
  .lesson summary { grid-template-columns: auto 1fr auto; gap: 12px; padding: 16px; }
  .lesson-body { padding: 0 16px 20px; }
  .sliders { grid-template-columns: 1fr; }
  .glyphs { font-size: 100px; }
  .pl .av { display: none; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: .01ms !important; animation-iteration-count: 1 !important; transition-duration: .01ms !important; }
}

/* ================= v2: cont, clase, teme, online, lecții ================= */
.acct { border: 1px solid var(--line); background: var(--surface); border-radius: 999px; padding: 7px 14px; font-size: 13px; font-weight: 600; max-width: 130px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; flex: none; }
.acct:hover { border-color: var(--ink); }
.acct.on { background: var(--ink); color: var(--bg); border-color: var(--ink); }
.dlg { border: 1px solid var(--ink); border-radius: 24px; padding: 24px; width: min(440px, calc(100vw - 32px)); background: var(--surface); color: var(--ink); box-shadow: 8px 8px 0 var(--lime), 8px 8px 0 1.5px var(--ink); }
.dlg::backdrop { background: rgba(10, 10, 8, .55); backdrop-filter: blur(4px); }
.dlg-head { display: flex; justify-content: space-between; align-items: center; margin-bottom: 18px; }
.dlg-head h3 { font-size: 1.9rem; }
.dlg form { display: block; }
.dlg .field { margin-bottom: 12px; }
.dlg-actions { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 16px; }
.err { color: var(--bad); font-size: 14px; min-height: 1.4em; margin: 4px 0 10px; }
textarea { font: inherit; padding: 11px 14px; border-radius: 12px; border: 1px solid var(--line); background: var(--bg); color: var(--ink); width: 100%; resize: vertical; }
.field select, select { padding: 11px 14px; border-radius: 12px; border: 1px solid var(--line); background: var(--bg); color: var(--ink); font: inherit; width: 100%; }
.field.grow { flex: 1; }

/* lecții: blocuri */
.lesson-body h4 { font: 700 1.25rem var(--display); letter-spacing: -.02em; margin-top: 6px; }
.lesson-body ul { padding-left: 20px; display: grid; gap: 6px; }
.lesson-body a { text-decoration: underline; text-underline-offset: 3px; }
.formula { font: 500 15px/1.7 var(--mono); padding: 14px 18px; border-radius: 14px; background: #11110e; color: #d2f53c; border: 1px solid rgba(210, 245, 60, .35); overflow-x: auto; white-space: pre-wrap; }

/* clase */
.gate { max-width: 640px; margin-top: 28px; display: grid; gap: 14px; justify-items: start; }
.gate h3 { font-size: 2rem; }
.inline-form { display: flex; gap: 12px; align-items: end; margin-top: 28px; flex-wrap: wrap; }
.class-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 14px; margin-top: 14px; }
.class-card { text-decoration: none; display: block; min-height: 150px; transition: transform .2s; }
.class-card:hover { transform: translateY(-4px); }
.class-card h3 { font-size: 1.7rem; margin-bottom: 10px; padding-right: 50px; }
.class-card .go { position: absolute; right: 16px; top: 16px; width: 40px; height: 40px; border-radius: 50%; border: 1.5px solid var(--ink); display: grid; place-items: center; }
.class-card:hover .go { background: var(--lime); color: var(--on-lime); }
.code { display: inline-block; font: 700 1.3rem var(--mono); letter-spacing: .18em; padding: 6px 12px; border-radius: 10px; background: var(--lime); color: var(--on-lime); margin-bottom: 8px; }
.back { display: block; width: fit-content; margin-bottom: 18px; font: 500 13px var(--mono); text-decoration: none; color: var(--muted); }
.back:hover { color: var(--ink); }
.class-head { display: flex; flex-wrap: wrap; justify-content: space-between; align-items: end; gap: 20px; }
.code-big { display: flex; align-items: center; gap: 12px; padding: 10px 14px; border: 1.5px dashed var(--ink); border-radius: 18px; }
.code-big small { font: 500 11px var(--mono); text-transform: uppercase; letter-spacing: .1em; color: var(--muted); }
.code-big b { font: 700 1.8rem var(--mono); letter-spacing: .2em; }
.asg-list { display: grid; gap: 10px; }
.asg { display: flex; justify-content: space-between; align-items: center; gap: 16px; text-decoration: none; padding: 18px 22px; transition: border-color .15s, transform .15s; }
.asg:hover { border-color: var(--ink); transform: translateX(4px); }
.asg h3 { font-size: 1.4rem; }
.chip.good { background: var(--lime); color: var(--on-lime); border-color: var(--on-lime); font-weight: 700; }
.chip.bad { color: var(--bad); border-color: var(--bad); }
.chip.warn { background: var(--ink); color: var(--bg); border-color: var(--ink); }
.two-col { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; align-items: start; }
.two-col.wide-left { grid-template-columns: 1.4fr 1fr; margin-top: 24px; }
.row2 { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; align-items: end; }
.qrev { display: grid; grid-template-columns: auto 1fr; gap: 14px; padding: 18px 0; border: 0; border-top: 1px solid var(--line); min-width: 0; }
.qrev:first-child { border-top: 0; }
.qn { width: 34px; height: 34px; border-radius: 50%; background: var(--ink); color: var(--bg); display: grid; place-items: center; font: 700 14px var(--mono); }
.qq { font: 600 1.15rem/1.35 var(--display); letter-spacing: -.01em; margin-bottom: 10px; white-space: pre-wrap; }
.rev-opts { display: grid; gap: 6px; }
.ro { display: flex; align-items: center; gap: 12px; padding: 10px 14px; border-radius: 12px; border: 1.5px solid var(--line); background: var(--bg); position: relative; }
.ro span { font: 600 12px var(--mono); color: var(--muted); width: 18px; }
.ro i { margin-left: auto; font: 500 11px var(--mono); font-style: normal; opacity: .7; }
.ro.right { background: var(--lime); color: var(--on-lime); border-color: var(--on-lime); }
.ro.right span { color: var(--on-lime); }
.ro.wrong { border-color: var(--bad); color: var(--bad); }
.ro.pick { cursor: pointer; }
.ro.pick:hover { border-color: var(--ink); }
.ro.pick input { position: absolute; opacity: 0; pointer-events: none; }
.ro.pick:has(input:checked) { background: var(--ink); color: var(--bg); border-color: var(--ink); }
.ro.pick:has(input:checked) span { color: var(--lime); }
.ro.pick:has(input:focus-visible) { outline: 2px solid var(--ink); outline-offset: 2px; }
.quiz-foot { display: flex; justify-content: space-between; align-items: center; margin-top: 10px; padding-top: 18px; border-top: 1px solid var(--line); }
.score-card { display: flex; align-items: baseline; gap: 18px; margin-top: 24px; }
.score-card b { font: 700 5rem/1 var(--display); letter-spacing: -.06em; }
.score-card small { font-size: 2rem; opacity: .4; }
.bar-row { display: grid; grid-template-columns: 1fr 90px 44px; gap: 12px; align-items: center; padding: 8px 0; font-size: 14px; border-top: 1px solid var(--line); }
.bar-row span { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.bar { height: 8px; border-radius: 99px; background: var(--surface-2); overflow: hidden; }
.bar i { display: block; height: 100%; background: var(--ink); }
.bar-row b { font: 600 13px var(--mono); text-align: right; }
.mini-h { font: 600 12px var(--mono); text-transform: uppercase; letter-spacing: .1em; color: var(--muted); margin-bottom: 12px; }

/* temă nouă */
.search { padding: 10px 14px; border-radius: 12px; border: 1px solid var(--line); background: var(--bg); color: var(--ink); font: inherit; width: 100%; }
.bank { display: grid; gap: 8px; max-height: 420px; overflow-y: auto; margin-top: 12px; padding-right: 4px; }
.bq { display: flex; justify-content: space-between; align-items: center; gap: 12px; padding: 12px 14px; border: 1px solid var(--line); border-radius: 14px; background: var(--bg); }
.bq p { font-size: 14px; margin-top: 6px; }
.opt-row { display: flex; gap: 10px; align-items: center; margin-bottom: 8px; }
.opt-row input[type=radio] { accent-color: var(--ink); width: 20px; height: 20px; flex: none; }
.opt-row .mo { flex: 1; padding: 10px 14px; border-radius: 12px; border: 1px solid var(--line); background: var(--bg); color: var(--ink); font: inherit; }
.dq { position: relative; padding: 12px 34px 12px 0; border-top: 1px solid var(--line); }
.dq:first-child { border-top: 0; }
.dq-t { font-size: 14px; font-weight: 500; }
.dq-o { display: flex; flex-wrap: wrap; gap: 4px; margin-top: 6px; }
.dq-o span { font: 12px var(--mono); padding: 2px 8px; border-radius: 99px; border: 1px solid var(--line); }
.dq-o span.right { background: var(--lime); color: var(--on-lime); border-color: var(--on-lime); }
.rm { position: absolute; right: 0; top: 10px; width: 26px; height: 26px; border-radius: 50%; border: 0; background: var(--surface-2); font-size: 12px; }
.rm:hover { background: var(--bad); color: #fff; }
.note { padding: 12px 14px; border-radius: 12px; background: var(--surface-2); font-size: 14px; border-left: 3px solid var(--lime); }

/* online */
.online { background: var(--ink) !important; color: var(--bg); display: grid; gap: 18px; }
.online h4 { color: color-mix(in srgb, var(--bg) 60%, transparent) !important; }
.online .lead { color: color-mix(in srgb, var(--bg) 70%, transparent); }
.online .opt { background: transparent; color: var(--bg); border-color: color-mix(in srgb, var(--bg) 30%, transparent); }
.online .opt[aria-pressed="true"] { background: var(--lime); color: var(--on-lime); border-color: var(--lime); }
.online .btn { border-color: var(--bg); }
.online .btn.ghost { color: var(--bg); background: transparent; }
.online .btn.lime { border-color: var(--lime); }
.online-head { display: flex; justify-content: space-between; gap: 16px; align-items: start; flex-wrap: wrap; }
.live-chip { background: transparent; color: var(--bg); border-color: color-mix(in srgb, var(--bg) 30%, transparent); }
.join-row { display: flex; gap: 8px; max-width: 360px; }
.join-row input { flex: 1; min-width: 0; padding: 12px 16px; border-radius: 999px; border: 1.5px solid color-mix(in srgb, var(--bg) 35%, transparent); background: transparent; color: var(--bg); font: 600 15px var(--mono); letter-spacing: .15em; }
.join-row input::placeholder { color: color-mix(in srgb, var(--bg) 45%, transparent); letter-spacing: .08em; }
.join-row .btn { background: var(--bg); color: var(--ink); }
.waiting { display: flex; gap: 18px; align-items: center; }
.room-code { font: 700 3rem/1 var(--mono); letter-spacing: .25em; color: var(--lime); margin-top: 6px; }
.spin { width: 36px; height: 36px; border-radius: 50%; border: 4px solid color-mix(in srgb, var(--bg) 25%, transparent); border-top-color: var(--lime); animation: spin 1s linear infinite; flex: none; }
@keyframes spin { to { transform: rotate(360deg); } }

@media (max-width: 980px) { .two-col, .two-col.wide-left { grid-template-columns: 1fr; } }
@media (max-width: 680px) {
  .acct { max-width: 90px; padding: 7px 10px; }
  .row2 { grid-template-columns: 1fr; }
  .score-card b { font-size: 3.6rem; }
  .bar-row { grid-template-columns: 1fr 60px 40px; }
  .room-code { font-size: 2.2rem; }
}

/* suprafețe întunecate fixe (lime rămâne lizibil în ambele teme) */
.online, .b-arena, .ticker { --bg: #f0eee6; --ink: #11110e; --surface-2: #21211d; --line: rgba(240, 238, 230, .14); }
.ticker { background: #11110e; color: #f0eee6; border-color: #11110e; }
.b-arena { background: #11110e !important; color: #f0eee6; }
.online { background: #11110e !important; color: #f0eee6; }
.ro.pick:has(input:checked) span { color: var(--bg); opacity: .7; }

/* ================= animații ================= */
/* apariție la scroll (clasele sunt puse de fx.js și scoase după ce se termină) */
.rv { opacity: 0; transform: translateY(26px) scale(.985); }
.rv.in { opacity: 1; transform: none; transition: opacity .7s cubic-bezier(.2, .7, .2, 1), transform .7s cubic-bezier(.2, .7, .2, 1); }

/* hero: intrare pe rând */
.hero h1 span { animation: lineIn .9s cubic-bezier(.2, .8, .2, 1) both; }
.hero h1 span:nth-child(1) { animation-delay: .05s; }
.hero h1 span:nth-child(2) { animation-delay: .17s; }
.hero h1 span:nth-child(3) { animation-delay: .29s; }
.hero h1 .hl { animation: hlIn 1s cubic-bezier(.3, 1.4, .5, 1) .55s both; }
.hero > .eyebrow { animation: fadeUp .7s ease both; }
.hero .lead { animation: fadeUp .8s ease .45s both; }
.hero .cta { animation: fadeUp .8s ease .6s both; }
@keyframes lineIn { from { opacity: 0; transform: translateY(60%) skewY(4deg); filter: blur(6px); } to { opacity: 1; transform: none; filter: none; } }
@keyframes hlIn { from { opacity: 0; transform: scale(.7) rotate(-8deg); } to { opacity: 1; transform: rotate(-1.5deg); } }
@keyframes fadeUp { from { opacity: 0; transform: translateY(18px); } to { opacity: 1; transform: none; } }

/* simboluri matematice care plutesc în hero */
.hero { position: relative; }
.floaties { position: absolute; inset: -20px 0 0; pointer-events: none; z-index: -1; overflow: visible; }
.floaties span { position: absolute; left: var(--x); top: var(--y); font: 700 var(--s, 90px)/1 var(--display); color: var(--ink); opacity: .07; animation: floaty var(--t, 9s) ease-in-out var(--d, 0s) infinite alternate; will-change: transform; }
@keyframes floaty { from { transform: translate3d(0, 0, 0) rotate(-6deg); } to { transform: translate3d(14px, -26px, 0) rotate(8deg); } }

/* meniu: pastila care alunecă */
.nav-links { position: relative; }
.nav-pill { position: absolute; top: 0; left: 0; border-radius: 999px; background: var(--ink); z-index: 0; pointer-events: none;
  transition: transform .5s cubic-bezier(.3, 1.25, .5, 1), width .5s cubic-bezier(.3, 1.25, .5, 1), height .3s, opacity .3s; }
.nav-links a { position: relative; z-index: 1; }
.has-pill .nav-links a[aria-current="page"], .nav-links.has-pill a[aria-current="page"] { background: transparent; color: var(--bg); }
.nav-links:has(.nav-pill) a[aria-current="page"] { background: transparent; color: var(--bg); }

/* butoane */
.btn svg { transition: transform .25s cubic-bezier(.3, 1.4, .5, 1); }
.btn:hover svg { transform: translate(3px, -3px); }

/* progres: barele cresc din stânga */
.prog > i, .bar i { transform-origin: left center; animation: grow 1.1s cubic-bezier(.2, .7, .2, 1) .15s both; }
@keyframes grow { from { transform: scaleX(0); } to { transform: scaleX(1); } }

/* lecții */
.lesson[open] .lesson-body { animation: fadeUp .45s cubic-bezier(.2, .7, .2, 1) both; }
.lesson .tick { transition: transform .3s cubic-bezier(.3, 1.6, .5, 1), background .2s; }
.lesson.done .tick { animation: pop .5s cubic-bezier(.3, 1.6, .5, 1); }
.lesson summary:hover .num { transform: translateX(4px); }
.lesson .num { transition: transform .25s; }
@keyframes pop { 0% { transform: scale(.4); } 60% { transform: scale(1.25); } 100% { transform: scale(1); } }

/* arenă */
.ans.right { animation: pop .5s cubic-bezier(.3, 1.6, .5, 1); }
.ans.wrong { animation: shake .45s ease; }
.ans.picked { animation: pick .25s ease; }
@keyframes shake { 0%, 100% { transform: translateX(0); } 20% { transform: translateX(-8px); } 40% { transform: translateX(7px); } 60% { transform: translateX(-5px); } 80% { transform: translateX(3px); } }
@keyframes pick { from { transform: scale(.97); } to { transform: scale(1); } }
.ring.low b { animation: tick 1s ease-in-out infinite; color: var(--bad); }
@keyframes tick { 0%, 100% { transform: scale(1); } 50% { transform: scale(1.18); } }
.pl.lead-p { animation: pop .5s cubic-bezier(.3, 1.6, .5, 1); }
.result h2 { animation: lineIn .9s cubic-bezier(.2, .8, .2, 1) both; }
.result .final > div { animation: fadeUp .7s ease both; }
.result .final > div:nth-child(2) { animation-delay: .15s; }
.result .win b { animation: hlIn .9s cubic-bezier(.3, 1.4, .5, 1) .4s both; }

/* chat */
.mini-chat div { animation: fadeUp .6s ease both; }
.mini-chat div:nth-child(1) { animation-delay: .3s; } .mini-chat div:nth-child(2) { animation-delay: 1s; }
.badge.on i { animation: pop .6s cubic-bezier(.3, 1.6, .5, 1) both; }
.glyphs { animation: floaty 10s ease-in-out infinite alternate; }

/* confetti */
.confetti { position: fixed; inset: 0; width: 100vw; height: 100vh; pointer-events: none; z-index: 90; }

/* ticker: se oprește când treci cu mouse-ul */
.ticker:hover .ticker-track { animation-play-state: paused; }

@media (prefers-reduced-motion: reduce) {
  .rv { opacity: 1; transform: none; }
  .floaties, .confetti { display: none; }
}

/* ===== animații v2 (fără lime intermitent) ===== */
/* carduri 3D care se înclină după mouse (transformul vine din fx.js) */
.bento a.card, .class-card, .asg, .stat, .bq { transition: transform .35s cubic-bezier(.2, .7, .2, 1), box-shadow .35s, border-color .2s; will-change: transform; }
.bento a.card:hover, .class-card:hover { box-shadow: 0 24px 50px -24px rgba(0, 0, 0, .45); border-color: var(--ink); }
.bento a.card.tilting, .class-card.tilting { transition: transform .08s linear, box-shadow .35s, border-color .2s; }

/* butoane: apăsare + magnetic */
.btn { transition: transform .2s cubic-bezier(.3, 1.3, .5, 1), box-shadow .2s, background .15s; }
.btn:active { transform: scale(.95) !important; }
.opt, .ans, .seg button, .sugg button { transition: transform .18s cubic-bezier(.3, 1.3, .5, 1), border-color .15s, background .15s, color .15s; }
.opt:active, .sugg button:active { transform: scale(.96); }
.sugg button:hover { transform: translateX(4px); }

/* simboluri care urmăresc cursorul (strat de adâncime) */
.floaties span { translate: calc(var(--px, 0) * var(--k, 18) * 1px) calc(var(--py, 0) * var(--k, 18) * 1px); transition: translate .5s cubic-bezier(.2, .7, .2, 1); }
.floaties span:nth-child(2n) { --k: 34; } .floaties span:nth-child(3n) { --k: -26; } .floaties span:nth-child(4) { --k: 48; }

/* bară de progres la scroll */
.scrollbar { position: fixed; top: 0; left: 0; right: 0; height: 3px; background: var(--ink); transform: scaleX(0); transform-origin: left; z-index: 80; pointer-events: none; }

/* lecții: conținutul intră pe rând când deschizi */
.lesson[open] .lesson-body > * { animation: fadeUp .5s cubic-bezier(.2, .7, .2, 1) both; }
.lesson[open] .lesson-body > :nth-child(2) { animation-delay: .05s; } .lesson[open] .lesson-body > :nth-child(3) { animation-delay: .1s; }
.lesson[open] .lesson-body > :nth-child(4) { animation-delay: .15s; } .lesson[open] .lesson-body > :nth-child(5) { animation-delay: .2s; }
.lesson[open] .lesson-body > :nth-child(6) { animation-delay: .25s; } .lesson[open] .lesson-body > :nth-child(7) { animation-delay: .3s; }
.lesson[open] .lesson-body > :nth-child(n+8) { animation-delay: .35s; }
.lesson summary { transition: padding-left .25s cubic-bezier(.2, .7, .2, 1); }
.lesson summary:hover { padding-left: 32px; }

/* meniu: linkurile se ridică la hover */
.nav-links a { transition: color .15s, transform .25s cubic-bezier(.3, 1.4, .5, 1); }
.nav-links a:hover { transform: translateY(-2px); }

/* etichete și cipuri */
.chip { transition: transform .2s cubic-bezier(.3, 1.4, .5, 1); }
.chip:hover { transform: translateY(-2px) rotate(-2deg); }

/* titlurile mari de pagină intră cu o ușoară ridicare */
.page-h { animation: lineIn .8s cubic-bezier(.2, .8, .2, 1) both; }
.eyebrow { animation: fadeUp .6s ease both; }
.lead { animation: fadeUp .7s ease .15s both; }

@media (prefers-reduced-motion: reduce) { .scrollbar { display: none; } }

/* buton limbă */
.icon-btn.lang { width: auto; min-width: 40px; padding: 0 10px; border: 1px solid var(--line); border-radius: 999px; font: 700 11px var(--mono); letter-spacing: .06em; }
.icon-btn.lang:hover { border-color: var(--ink); }

.depth-sel { width: auto; padding: 7px 10px; font-size: 13px; border-radius: 999px; border: 1px solid var(--line); background: var(--surface); color: var(--ink); font-weight: 500; }
.depth-sel:hover { border-color: var(--ink); }

/* chat: tabele și butonul „explicație detaliată” */
.msg table { border-collapse: collapse; margin: 8px 0; font-size: 14px; display: block; overflow-x: auto; max-width: 100%; }
.msg th, .msg td { border: 1px solid var(--line); padding: 5px 10px; text-align: center; white-space: nowrap; }
.msg th { background: color-mix(in srgb, var(--ink) 8%, transparent); font-weight: 600; }
.msg .more { margin-top: 12px; }
.msg.a .src + .more, .msg.a .more { display: inline-flex; }

/* notație matematică: indici, exponenți, vectori cu săgeată */
sub, sup { font-size: .72em; line-height: 0; font-family: inherit; }
sub { vertical-align: -.28em; }
sup { vertical-align: .45em; }
.vec { position: relative; display: inline-block; padding-top: .42em; font-style: italic; }
.vec::before { content: '→'; position: absolute; top: -.28em; left: 0; right: 0; text-align: center; font-size: .78em; line-height: 1; font-style: normal; }
code .vec::before, .formula .vec::before { top: -.34em; }