:root {
  --bg: #F8F7F4; --surface: #FFFFFF; --sunken: #F1F3F7;
  --ink: #0F172A; --muted: #475569; --faint: #64748B; --line: #E5E7EB;
  --primary: #2563EB; --primary-ink: #1D4ED8; --primary-soft: #EAF1FE;
  --coral: #C2410C; --coral-bg: #FF6B45; --coral-soft: #FFF0EA;
  --green: #047857; --green-soft: #E6F7EF;
  --violet: #6D28D9; --violet-soft: #F1ECFE;
  --amber: #B45309; --amber-soft: #FEF5E3;
  --red: #B91C1C; --red-soft: #FDECEC;
  --navy: #172036;
  --r-lg: 24px; --r-md: 16px; --r-sm: 12px;
  --shadow: 0 1px 2px rgb(15 23 42 / .04), 0 8px 24px -12px rgb(15 23 42 / .12);
  --font: 'Figtree', system-ui, sans-serif; --mono: 'JetBrains Mono', ui-monospace, monospace;
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--bg); color: var(--ink); font: 16px/1.55 var(--font); }
a { color: inherit; text-decoration: none; }
button, input, select { font: inherit; color: inherit; }
button { cursor: pointer; border: 0; background: none; }
svg { width: 24px; height: 24px; fill: none; stroke: currentColor; stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; flex-shrink: 0; }
:focus-visible { outline: 3px solid color-mix(in srgb, var(--primary) 55%, transparent); outline-offset: 2px; border-radius: 10px; }
.katex { font-size: 1.08em; }
.katex-display { margin: .6em 0; overflow-x: auto; overflow-y: hidden; padding: 2px 0; }

/* ── Layout ── */
.app { min-height: 100dvh; }
main { max-width: 1040px; margin: 0 auto; padding: 28px 16px 120px; outline: none; }
.nav { position: fixed; z-index: 30; left: 12px; right: 12px; bottom: 12px; display: flex; gap: 4px; padding: 6px; background: rgb(255 255 255 / .92); backdrop-filter: blur(12px); border: 1px solid var(--line); border-radius: 22px; box-shadow: 0 10px 30px -10px rgb(15 23 42 / .25); }
.nav a { flex: 1; display: flex; flex-direction: column; align-items: center; gap: 2px; padding: 8px 4px; min-height: 56px; justify-content: center; border-radius: 16px; font-size: 13px; font-weight: 600; color: var(--faint); transition: background .2s, color .2s; }
.nav a:hover { color: var(--ink); }
.nav a.active { background: var(--primary-soft); color: var(--primary); }
.nav .brand { display: none; }
@media (min-width: 960px) {
  .app { display: grid; grid-template-columns: 232px 1fr; }
  .nav { position: sticky; top: 0; height: 100dvh; left: auto; right: auto; bottom: auto; flex-direction: column; gap: 6px; padding: 28px 16px; border: 0; border-right: 1px solid var(--line); border-radius: 0; box-shadow: none; background: var(--surface); }
  .nav a { flex: 0 0 auto; flex-direction: row; justify-content: flex-start; gap: 12px; padding: 12px 14px; min-height: 48px; font-size: 15px; }
  .nav .brand { display: flex; font-size: 20px; font-weight: 800; color: var(--ink); margin-bottom: 18px; }
  main { padding: 44px 40px 60px; width: 100%; }
}
.brand-mark { display: inline-grid; place-items: center; width: 34px; height: 34px; border-radius: 10px; background: var(--primary); color: #fff; font-size: 18px; }

/* ── Type ── */
h1 { font-size: clamp(30px, 5vw, 40px); line-height: 1.1; margin: 0; font-weight: 800; letter-spacing: -.02em; }
h2 { font-size: 22px; line-height: 1.25; margin: 0; font-weight: 700; letter-spacing: -.01em; }
h3 { font-size: 17px; margin: 0; font-weight: 700; }
.muted { color: var(--muted); }
.eyebrow { font-size: 13px; font-weight: 700; letter-spacing: .08em; text-transform: uppercase; color: var(--faint); }
.small { font-size: 14px; }
.mono { font-family: var(--mono); font-size: 13.5px; }

/* ── Building blocks ── */
.stack > * + * { margin-top: 28px; }
.row { display: flex; align-items: center; gap: 12px; }
.between { justify-content: space-between; }
.grid2 { display: grid; gap: 28px; }
@media (min-width: 960px) { .grid2 { grid-template-columns: 1fr 1fr; align-items: start; } }
.card { background: var(--surface); border: 1px solid var(--line); border-radius: var(--r-lg); padding: 20px; box-shadow: var(--shadow); }
.link { color: var(--primary); font-weight: 700; padding: 8px 0; }
.link:hover { color: var(--primary-ink); }
.pill { display: inline-flex; align-items: center; gap: 6px; padding: 6px 12px; border-radius: 999px; font-size: 14px; font-weight: 700; white-space: nowrap; }
.pill svg { width: 18px; height: 18px; }
.tone-blue { background: var(--primary-soft); color: var(--primary); }
.tone-coral { background: var(--coral-soft); color: var(--coral); }
.tone-green { background: var(--green-soft); color: var(--green); }
.tone-violet { background: var(--violet-soft); color: var(--violet); }
.tone-amber { background: var(--amber-soft); color: var(--amber); }
.tone-red { background: var(--red-soft); color: var(--red); }
.ico { display: grid; place-items: center; width: 48px; height: 48px; border-radius: 14px; flex-shrink: 0; }

.btn { display: inline-flex; align-items: center; justify-content: center; gap: 10px; min-height: 52px; padding: 0 22px; border-radius: var(--r-md); font-weight: 700; transition: background .2s, box-shadow .2s, opacity .2s; }
.btn svg { width: 20px; height: 20px; }
.btn-primary { background: var(--primary); color: #fff; box-shadow: 0 8px 20px -8px rgb(37 99 235 / .6); }
.btn-primary:hover { background: var(--primary-ink); }
.btn-soft { background: var(--primary-soft); color: var(--primary); }
.btn-soft:hover { background: #DCE7FD; }
.btn-ghost { border: 1px solid var(--line); background: var(--surface); }
.btn-ghost:hover { background: var(--sunken); }
.btn[disabled] { opacity: .5; cursor: not-allowed; }
.w-full { width: 100%; }
.icon-btn { display: grid; place-items: center; width: 44px; height: 44px; border-radius: 14px; border: 1px solid var(--line); background: var(--surface); }
.icon-btn:hover { background: var(--sunken); }

.seg { display: flex; padding: 5px; background: var(--surface); border: 1px solid var(--line); border-radius: 18px; }
.seg button { flex: 1; min-height: 46px; border-radius: 13px; font-weight: 700; color: var(--muted); transition: background .2s, color .2s; }
.seg button[aria-pressed="true"] { background: var(--primary); color: #fff; }

.chips { display: flex; gap: 8px; overflow-x: auto; padding: 2px 2px 6px; scrollbar-width: none; }
.chips::-webkit-scrollbar { display: none; }
.chip { flex-shrink: 0; min-height: 44px; padding: 0 18px; border-radius: 999px; border: 1px solid var(--line); background: var(--surface); font-weight: 600; font-size: 15px; transition: background .2s, color .2s, border-color .2s; }
.chip:hover { border-color: #CBD5E1; }
.chip[aria-pressed="true"] { background: var(--primary); border-color: var(--primary); color: #fff; }

.search { position: relative; }
.search svg { position: absolute; left: 16px; top: 50%; translate: 0 -50%; color: var(--faint); }
.search input { width: 100%; min-height: 54px; padding: 0 16px 0 50px; border-radius: var(--r-md); border: 1px solid transparent; background: var(--sunken); font-size: 16px; }
.search input:focus { outline: none; border-color: var(--primary); background: var(--surface); }
.results { margin-top: 8px; display: grid; gap: 6px; }

.bar { height: 10px; background: #E8ECF3; border-radius: 99px; overflow: hidden; }
.bar > i { display: block; height: 100%; background: var(--primary); border-radius: 99px; transition: width .4s ease; }

.list-row { display: flex; align-items: center; gap: 14px; width: 100%; text-align: left; padding: 14px 16px; border-radius: var(--r-md); background: var(--sunken); transition: background .2s; }
.list-row:hover { background: #E7EBF2; }
.list-row .grow { flex: 1; min-width: 0; }
.list-row .title { font-weight: 700; }
.status { display: grid; place-items: center; width: 30px; height: 30px; border-radius: 50%; flex-shrink: 0; }
.status svg { width: 16px; height: 16px; }
.status.done { background: #10B981; color: #fff; }
.status.doing { background: var(--primary); color: #fff; }
.status.todo { border: 2px solid #CBD5E1; }

/* ── Home ── */
.hello-date { color: var(--muted); font-weight: 500; }
.featured { display: grid; grid-auto-flow: column; grid-auto-columns: minmax(250px, 1fr); gap: 14px; overflow-x: auto; padding-bottom: 6px; scrollbar-width: none; }
.featured::-webkit-scrollbar { display: none; }
.feat { position: relative; overflow: hidden; display: flex; flex-direction: column; gap: 6px; padding: 20px; border-radius: var(--r-lg); min-height: 170px; transition: box-shadow .2s; }
.feat:hover { box-shadow: var(--shadow); }
.feat h3 { font-size: 20px; color: var(--ink); }
.feat p { margin: 0; color: var(--muted); }
.feat .go { margin-top: auto; display: flex; align-items: center; gap: 6px; font-weight: 700; }
.feat .go svg { width: 18px; height: 18px; }
.feat .deco { position: absolute; right: -18px; top: -18px; width: 110px; height: 110px; opacity: .18; stroke-width: 1.5; }
.dark-card { display: flex; align-items: center; gap: 16px; padding: 20px; border-radius: var(--r-lg); background: var(--navy); color: #fff; transition: background .2s; }
.dark-card:hover { background: #1E2945; }
.dark-card .ico { background: var(--coral-bg); color: #fff; }
.dark-card .eyebrow { color: #A7B1C6; }

/* ── Temas ── */
.block-head { display: flex; align-items: center; gap: 14px; padding-bottom: 16px; margin-bottom: 14px; border-bottom: 1px solid var(--line); }
.block-head .grow { flex: 1; }
.units { display: grid; gap: 10px; }
.theory { font-size: 17px; line-height: 1.7; }
.formula { padding: 14px 16px; border-radius: var(--r-sm); background: var(--sunken); overflow-x: auto; }
.formulas { display: grid; gap: 10px; }
@media (min-width: 640px) { .formulas { grid-template-columns: 1fr 1fr; } }

/* ── Práctica ── */
.modes { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; }
.mode { display: flex; flex-direction: column; align-items: center; gap: 8px; padding: 16px 8px; text-align: center; border-radius: 20px; background: var(--surface); border: 2px solid var(--line); transition: border-color .2s, background .2s; }
.mode:hover { border-color: #BFD3FB; }
.mode[aria-pressed="true"] { border-color: var(--primary); background: #F7FAFF; }
.mode b { font-size: 15px; line-height: 1.2; }
.mode span { font-size: 13px; color: var(--muted); }
.cta-card { display: flex; align-items: center; gap: 16px; width: 100%; text-align: left; padding: 20px 22px; border-radius: 22px; background: var(--primary); color: #fff; box-shadow: 0 14px 30px -14px rgb(37 99 235 / .7); transition: background .2s; }
.cta-card:hover { background: var(--primary-ink); }
.cta-card .grow { flex: 1; }
.cta-card small { display: block; font-size: 14px; opacity: .9; font-weight: 600; }
.stats3 { display: grid; grid-template-columns: repeat(3, 1fr); text-align: center; }
.stats3 > div + div { border-left: 1px solid var(--line); }
.stats3 b { display: block; font-size: 28px; font-weight: 800; letter-spacing: -.02em; }

/* ── Quiz ── */
.quiz-top { display: flex; align-items: center; gap: 12px; }
.quiz-top .bar { flex: 1; }
.timer { font-family: var(--mono); font-weight: 500; min-width: 64px; text-align: right; }
.timer.low { color: var(--red); }
.q-card { padding: 26px 22px; }
.q-text { font-size: 19px; line-height: 1.65; margin: 10px 0 22px; overflow-wrap: anywhere; }
.answer { display: flex; gap: 10px; }
.answer input { flex: 1; min-width: 0; min-height: 56px; padding: 0 18px; border-radius: var(--r-md); border: 2px solid var(--line); background: var(--surface); font-family: var(--mono); font-size: 20px; }
.answer input:focus { outline: none; border-color: var(--primary); }
.answer input.ok { border-color: #10B981; background: var(--green-soft); }
.answer input.ko { border-color: #EF4444; background: var(--red-soft); }
.hint-help { margin-top: 8px; font-size: 14px; color: var(--muted); }
.err { color: var(--red); font-weight: 600; font-size: 14px; margin-top: 8px; }
.feedback { margin-top: 18px; padding: 16px 18px; border-radius: var(--r-md); }
.feedback.ok { background: var(--green-soft); color: #065F46; }
.feedback.ko { background: var(--red-soft); color: #7F1D1D; }
.feedback h3 { display: flex; align-items: center; gap: 8px; }
.steps { margin: 12px 0 0; padding-left: 22px; color: var(--ink); }
.steps li { margin: 6px 0; }
.hints { margin-top: 16px; padding: 14px 18px; border-radius: var(--r-md); background: var(--amber-soft); }
.hints .steps { margin-top: 6px; }
.result-big { font-size: 64px; font-weight: 800; letter-spacing: -.03em; line-height: 1; }

/* ── Perfil ── */
.avatar { display: grid; place-items: center; width: 76px; height: 76px; border-radius: 22px; background: linear-gradient(135deg, #3B82F6, #1D4ED8); color: #fff; font-size: 30px; font-weight: 800; flex-shrink: 0; }
.kpis { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; }
.kpi { text-align: center; padding: 18px 8px; }
.kpi .ico { margin: 0 auto 10px; width: 44px; height: 44px; border-radius: 50%; }
.kpi b { display: block; font-size: 24px; font-weight: 800; font-family: var(--mono); letter-spacing: -.03em; }
.kpi span { font-size: 13px; color: var(--muted); font-weight: 600; }
.week { display: grid; grid-template-columns: repeat(7, 1fr); gap: 10px; align-items: end; height: 150px; margin-top: 18px; }
.week div { display: flex; flex-direction: column; justify-content: flex-end; align-items: center; gap: 8px; height: 100%; font-size: 13px; color: var(--faint); font-weight: 600; }
.week i { width: 100%; max-width: 44px; min-height: 6px; border-radius: 10px; background: var(--primary-soft); }
.week .today i { background: var(--primary); }
.week .today { color: var(--primary); }
.medals { display: grid; grid-template-columns: repeat(auto-fill, minmax(140px, 1fr)); gap: 10px; }
.medal { display: flex; flex-direction: column; align-items: center; text-align: center; gap: 6px; padding: 16px 10px; border-radius: var(--r-md); background: var(--sunken); }
.medal.locked { opacity: .55; }
.medal b { font-size: 14px; }
.medal span { font-size: 12.5px; color: var(--muted); }
.field { display: grid; gap: 6px; }
.field label { font-weight: 700; font-size: 14px; }
.field input, .field select { min-height: 50px; padding: 0 14px; border-radius: var(--r-sm); border: 1px solid var(--line); background: var(--surface); font-size: 16px; }
.field input:focus, .field select:focus { outline: none; border-color: var(--primary); }

.welcome { max-width: 480px; margin: 6vh auto 0; }

/* ── Reproductor de vídeo ── */
.video-layout { display: grid; gap: 20px; }
@media (min-width: 1100px) { .video-layout.has-list { grid-template-columns: 1fr 300px; align-items: start; } }
.player { position: relative; margin: 0; aspect-ratio: 16 / 9; background: #000; border-radius: 20px; overflow: hidden; color: #fff; box-shadow: 0 20px 40px -24px rgb(15 23 42 / .6); user-select: none; }
.player:focus-visible { outline: 3px solid var(--primary); outline-offset: 3px; }
.player.fs { border-radius: 0; }
.player video { width: 100%; height: 100%; display: block; object-fit: contain; cursor: pointer; }
.player video::cue { font-family: var(--font); font-size: clamp(15px, 2.4vw, 26px); background: rgb(0 0 0 / .72); }
.p-big { position: absolute; left: 50%; top: 50%; translate: -50% -50%; width: 76px; height: 76px; border-radius: 50%; display: grid; place-items: center; background: rgb(37 99 235 / .92); color: #fff; box-shadow: 0 10px 30px rgb(0 0 0 / .35); transition: opacity .2s, background .2s; }
.p-big:hover { background: var(--primary-ink); }
.p-big svg { width: 32px; height: 32px; fill: currentColor; margin-left: 4px; }
.player.playing .p-big { opacity: 0; pointer-events: none; }
.p-flash { position: absolute; left: 50%; top: 50%; translate: -50% -50%; padding: 10px 18px; border-radius: 14px; background: rgb(0 0 0 / .6); font-weight: 700; font-size: 18px; opacity: 0; pointer-events: none; }
.p-flash.on { animation: pflash .6s ease-out; }
@keyframes pflash { 0% { opacity: 1; } 70% { opacity: 1; } 100% { opacity: 0; } }
.p-ui { position: absolute; inset: auto 0 0 0; padding: 40px 12px 8px; background: linear-gradient(transparent, rgb(0 0 0 / .78)); transition: opacity .25s; }
.player.playing:not(.awake) .p-ui { opacity: 0; }
.player.playing:not(.awake) { cursor: none; }
.player:focus-within .p-ui { opacity: 1; }
.p-seek { position: relative; height: 22px; display: flex; align-items: center; cursor: pointer; }
.p-track { position: absolute; left: 0; right: 0; height: 5px; border-radius: 9px; background: rgb(255 255 255 / .25); overflow: hidden; transition: height .15s; }
.p-seek:hover .p-track { height: 8px; }
.p-track i { position: absolute; left: 0; top: 0; bottom: 0; }
.p-buf { background: rgb(255 255 255 / .35); }
.p-fill { background: var(--primary); }
.p-marks i { width: 3px; background: rgb(0 0 0 / .55); translate: -1px 0; }
.p-seek input { position: relative; width: 100%; margin: 0; height: 22px; opacity: 0; cursor: pointer; }
.p-seek input:focus-visible { opacity: 1; accent-color: var(--primary); }
.p-tip { position: absolute; bottom: 28px; translate: -50% 0; padding: 5px 9px; border-radius: 8px; background: rgb(15 23 42 / .92); font: 600 13px/1.3 var(--font); white-space: nowrap; text-align: center; pointer-events: none; }
.p-tip b { display: block; font-weight: 700; }
.p-row { display: flex; align-items: center; gap: 2px; }
.p-btn { display: grid; place-items: center; width: 44px; height: 44px; border-radius: 12px; color: #fff; transition: background .15s; }
.p-btn:hover { background: rgb(255 255 255 / .16); }
.p-btn svg { width: 22px; height: 22px; }
.p-btn[data-a="play"] svg { fill: currentColor; }
.p-btn[aria-pressed="true"] { color: #93C5FD; }
.p-vol { display: flex; align-items: center; }
.p-vol input { width: 0; opacity: 0; transition: width .2s, opacity .2s; accent-color: #fff; }
.p-vol:hover input, .p-vol:focus-within input { width: 80px; opacity: 1; margin-right: 8px; }
.p-time { font-size: 13px; padding: 0 6px; white-space: nowrap; }
.p-chap { flex: 1; min-width: 0; font-size: 13px; font-weight: 600; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; opacity: .9; }
.p-rate { width: auto; min-width: 50px; padding: 0 8px; font: 700 14px var(--mono); }
.p-speed { position: relative; }
.p-menu { position: absolute; right: 0; bottom: 52px; display: grid; min-width: 130px; padding: 6px; border-radius: 14px; background: rgb(15 23 42 / .96); box-shadow: 0 12px 30px rgb(0 0 0 / .4); }
.p-menu[hidden] { display: none; }
.p-menu button { text-align: left; padding: 10px 14px; border-radius: 9px; color: #fff; font-weight: 600; font-size: 14px; }
.p-menu button:hover, .p-menu button:focus-visible { background: rgb(255 255 255 / .12); outline: none; }
.p-menu button[aria-checked="true"] { color: #93C5FD; }
.p-menu button[aria-checked="true"]::after { content: ' ✓'; }
.p-err { position: absolute; inset: 0; display: grid; place-items: center; padding: 24px; text-align: center; background: #0F172A; font-weight: 600; }
.player.broken .p-ui, .player.broken .p-big { display: none; }
@media (max-width: 560px) { .p-vol, .p-chap, .p-btn[data-a="rew"], .p-btn[data-a="fwd"] { display: none; } .p-time { flex: 1; } .p-btn { width: 40px; } }
.chapters { display: grid; gap: 6px; margin-top: 14px; }
.chapter { display: flex; gap: 12px; align-items: baseline; text-align: left; padding: 10px 14px; border-radius: 12px; background: var(--sunken); font-weight: 600; transition: background .2s; }
.chapter:hover { background: #E7EBF2; }
.chapter.on { background: var(--primary-soft); color: var(--primary); }
.chapter .mono { color: var(--muted); min-width: 44px; }
.chapter.on .mono { color: var(--primary); }
.playlist { padding: 14px; display: grid; gap: 4px; }
.pl-item { display: flex; gap: 12px; align-items: center; text-align: left; padding: 10px; border-radius: 12px; font-weight: 600; transition: background .2s; }
.pl-item:hover { background: var(--sunken); }
.pl-item[aria-current="true"] { background: var(--primary-soft); color: var(--primary); }
.pl-n { display: grid; place-items: center; width: 30px; height: 30px; flex-shrink: 0; border-radius: 50%; background: var(--sunken); font-size: 13px; }
.pl-n svg { width: 16px; height: 16px; color: var(--green); }

@media (prefers-reduced-motion: reduce) { *, *::before, *::after { transition: none !important; animation: none !important; } }

/* ── Tema: explicación ── */
.tema-layout { display: grid; gap: 20px; align-items: start; }
@media (min-width: 1100px) { .tema-layout { grid-template-columns: minmax(0, 1fr) 340px; } .tema-aside { position: sticky; top: 24px; } }
.explain { padding: 26px clamp(18px, 3vw, 34px); font-size: 17px; line-height: 1.75; min-width: 0; }
.explain .lead { font-size: 18.5px; color: var(--ink); margin: 0 0 8px; padding-bottom: 18px; border-bottom: 1px solid var(--line); }
.explain h3 { font-size: 20px; margin: 28px 0 8px; letter-spacing: -.01em; }
.explain p { margin: 10px 0; max-width: 72ch; }
.explain ul, .explain ol { padding-left: 22px; margin: 10px 0; max-width: 72ch; }
.explain li { margin: 6px 0; }
.explain .katex-display { margin: 14px 0; }
.box { margin: 18px 0; padding: 14px 18px 12px; border-radius: var(--r-md); border-left: 4px solid; }
.box p { margin: 6px 0; }
.box-ejemplo { background: var(--primary-soft); border-color: var(--primary); }
.box-ojo { background: var(--amber-soft); border-color: #D97706; }
.box-title { display: flex; align-items: center; gap: 8px; font-weight: 700; font-size: 15px; }
.box-title svg { width: 18px; height: 18px; }
.box-ejemplo .box-title { color: var(--primary-ink); }
.box-ojo .box-title { color: var(--amber); }
.formulas.one { grid-template-columns: 1fr; }
.tool-cta { display: flex; align-items: center; gap: 14px; transition: border-color .2s; }
.tool-cta:hover { border-color: #BFD3FB; }
.tool-cta > span:nth-child(2) { flex: 1; display: grid; gap: 2px; }
.pager { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.pager a { display: flex; align-items: center; gap: 12px; padding: 16px; transition: border-color .2s; }
.pager a:hover { border-color: #BFD3FB; }
.pager a > span { display: grid; min-width: 0; }
.pager .next { justify-content: flex-end; text-align: right; grid-column: 2; }

/* ── Herramientas ── */
.sr { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); }
.tool-grid { display: grid; gap: 12px; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); }
.tool-card { display: flex; gap: 14px; align-items: flex-start; padding: 18px; border-radius: var(--r-lg); background: var(--surface); border: 1px solid var(--line); box-shadow: var(--shadow); transition: border-color .2s; }
.tool-card:hover { border-color: #BFD3FB; }
.tool-card > span:last-child { display: grid; gap: 2px; }
.tool-layout { display: grid; gap: 20px; align-items: start; }
.tool-layout > * { min-width: 0; }
@media (min-width: 1000px) { .tool-layout { grid-template-columns: 360px minmax(0, 1fr); } .tool-layout.wide-first { grid-template-columns: minmax(0, 1fr) 360px; } }
.calc-out { min-height: 120px; overflow-x: auto; }
.calc-out p { margin: 10px 0; }
.fx-row { display: flex; align-items: center; gap: 10px; }
.fx-row ~ .fx-row { margin-top: 8px; }
.fx-row input { flex: 1; min-width: 0; min-height: 46px; padding: 0 12px; border-radius: var(--r-sm); border: 1px solid var(--line); font: 500 16px var(--mono); }
.fx-row input:focus { outline: none; border-color: var(--primary); }
.swatch { display: inline-block; width: 12px; height: 12px; border-radius: 4px; flex-shrink: 0; }
.slider { display: flex; align-items: center; gap: 10px; }
.slider + .slider { margin-top: 8px; }
.slider input[type=range] { flex: 1; min-width: 0; accent-color: var(--primary); min-height: 32px; }
.slider output { min-width: 44px; text-align: right; }
.plot-wrap { position: relative; padding: 0; overflow: hidden; }
.plot-wrap canvas { display: block; width: 100%; height: clamp(320px, 62vh, 620px); touch-action: none; cursor: grab; }
.plot-wrap canvas:active { cursor: grabbing; }
.plot-tools { position: absolute; top: 12px; right: 12px; display: flex; gap: 6px; z-index: 2; }
.plot-tools .icon-btn { font-size: 20px; font-weight: 700; box-shadow: var(--shadow); }
.plot-tools svg { width: 20px; height: 20px; }
.plot-hint { position: absolute; left: 14px; bottom: 8px; margin: 0; pointer-events: none; }
.plot-tip { position: absolute; z-index: 5; min-width: 130px; padding: 8px 12px; border-radius: 10px; background: var(--navy); color: #fff; font-size: 13px; line-height: 1.5; pointer-events: none; box-shadow: 0 8px 20px rgb(0 0 0 / .2); }
.plot-tip .swatch { width: 9px; height: 9px; margin-right: 6px; }
.chart-wrap { position: relative; }
.chart-wrap svg { width: 100%; display: block; overflow: visible; }
.bar.on path { opacity: .85; }
.tbl { width: 100%; border-collapse: collapse; margin-top: 8px; font-size: 13.5px; }
.tbl th, .tbl td { padding: 6px 8px; text-align: right; border-bottom: 1px solid var(--line); }
.tbl th { color: var(--muted); font-weight: 600; }
.coords { display: grid; grid-template-columns: auto 1fr 1fr; gap: 8px; align-items: center; }
.coords input, .num-sm { min-height: 42px; width: 100%; padding: 0 10px; border-radius: 10px; border: 1px solid var(--line); font: 500 15px var(--mono); }
.num-sm { width: 76px; }
.chip-sm { min-height: 36px; padding: 0 12px; font-size: 13.5px; }
svg .grid { stroke: #EDF0F5; stroke-width: 1; }
svg .axis { stroke: #94A3B8; stroke-width: 1.25; }
svg .tick { fill: #64748B; font: 13px var(--font); text-anchor: middle; }
svg .muted-t { fill: #94A3B8; }
svg .tri { fill: rgb(37 99 235 / .1); stroke: var(--primary); stroke-width: 2.5; stroke-linejoin: round; }
svg .arc { fill: none; stroke: #E8590C; stroke-width: 2; }
svg .alab { fill: #9A3412; font: 700 14px var(--font); text-anchor: middle; }
svg .slab { fill: var(--ink); font: 600 14px var(--mono); text-anchor: middle; paint-order: stroke; stroke: #fff; stroke-width: 4px; }
svg .vlab { fill: var(--ink); font: 800 17px var(--font); }
svg .vdot { fill: var(--primary); stroke: #fff; stroke-width: 3; }
svg .vtx { cursor: grab; outline: none; }
svg .vtx:focus-visible .vdot { stroke: #F59E0B; stroke-width: 4; }
svg .unit { fill: none; stroke: #CBD5E1; stroke-width: 2; }
svg .radius { stroke: var(--ink); stroke-width: 2; }
svg .thin { stroke: #94A3B8; stroke-width: 1.25; stroke-dasharray: 4 4; }
svg .wave { fill: none; stroke-width: 2.5; }
svg .handle { cursor: grab; }
.legend { display: flex; flex-wrap: wrap; gap: 14px; font-size: 13.5px; color: var(--muted); margin-top: 6px; }
.legend span { display: inline-flex; align-items: center; gap: 6px; }
.legend i { width: 12px; height: 12px; border-radius: 3px; display: inline-block; }
.legend i.mk { height: 3px; width: 14px; background: #172036; border-radius: 2px; }
.trig-row { display: grid; grid-template-columns: 14px 64px 90px 1fr; gap: 10px; align-items: center; padding: 8px 0; border-bottom: 1px solid var(--line); }
.kv { display: grid; grid-template-columns: auto 1fr; gap: 8px 16px; align-items: baseline; }
.kv > span { color: var(--muted); font-size: 14px; }
.coef3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; }
.coef3 .field input { min-width: 0; text-align: center; font-family: var(--mono); }
.frac-in { display: grid; grid-template-columns: 1fr 90px 1fr; gap: 10px; align-items: end; }
.frac-in input, .frac-in select { min-width: 0; font-family: var(--mono); text-align: center; }
.mat { display: grid; gap: 8px; }
.mat input { min-height: 48px; min-width: 0; width: 100%; text-align: center; border-radius: 10px; border: 1px solid var(--line); font: 500 17px var(--mono); }
.mat input:focus, .coords input:focus, .num-sm:focus { outline: none; border-color: var(--primary); }
.ruffini { border-collapse: collapse; margin: 8px 0; font-size: 16px; }
.ruffini td { padding: 8px 14px; text-align: right; }
.ruffini tr td:first-child { border-right: 2px solid var(--ink); }
.ruffini tr:nth-child(2) td { border-bottom: 2px solid var(--ink); }
.ruffini .rest { background: var(--primary-soft); color: var(--primary); font-weight: 700; border-radius: 6px; }
.last-rolls { display: flex; flex-wrap: wrap; gap: 6px; align-items: center; margin-top: 10px; }
.roll { display: inline-grid; place-items: center; min-width: 34px; height: 30px; padding: 0 6px; border-radius: 8px; background: var(--sunken); font: 600 13px var(--mono); }
.stat-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(140px, 1fr)); gap: 10px; }
.stat-grid > div { display: grid; gap: 2px; padding: 10px 12px; border-radius: 12px; background: var(--sunken); }
.stat-grid b { font-size: 18px; }
.field textarea { padding: 12px 14px; border-radius: var(--r-sm); border: 1px solid var(--line); font: 15px/1.6 var(--mono); resize: vertical; }
.field textarea:focus { outline: none; border-color: var(--primary); }
@media (max-width: 480px) { .nav a { font-size: 11px; padding: 8px 2px; } .frac-in { grid-template-columns: 1fr 70px 1fr; } .trig-row { grid-template-columns: 14px 54px 80px 1fr; } .pager { grid-template-columns: 1fr; } .pager .next { grid-column: 1; } }
/* SVG de herramientas y gráficos (los iconos no llevan viewBox en el <svg>) */
#tool svg[viewBox]:not(.katex svg) { width: 100%; height: auto; fill: none; stroke: none; stroke-width: 1; }

/* ── Cuentas y clases ── */
.nav[hidden], .nav a[hidden] { display: none; }
.nav[hidden] + main { grid-column: 1 / -1; }   /* sin menú (bienvenida/acceso), el contenido ocupa todo el ancho */
.welcome form.stack > * + * { margin-top: 16px; }
.welcome form.stack > button.btn { margin-top: 22px; }
#amsg:empty, #npm:empty { display: none; }
.welcome button.link { display: block; margin: 0 auto; }
.code-in { min-height: 48px; width: 150px; padding: 0 14px; border-radius: var(--r-sm); border: 1px solid var(--line); font: 600 18px var(--mono); letter-spacing: .15em; text-transform: uppercase; }
.code-in:focus { outline: none; border-color: var(--primary); }
.code-chip { display: inline-grid; place-items: center; min-height: 52px; padding: 0 18px; border-radius: var(--r-md); background: var(--violet-soft); color: var(--violet); font-size: 24px; font-weight: 700; letter-spacing: .18em; }
.tbl.students th, .tbl.students td { text-align: left; white-space: nowrap; }
.tbl.students td:first-child { font-weight: 600; }