/* Álgebra con Valentina: texto grande (mín. 18px), alto contraste, foco visible para control remoto. */
:root {
  --bg: #0b1626;
  --card: #14233a;
  --card2: #1b2f4d;
  --line: #4a6a96;
  --text: #ffffff;
  --muted: #d3deee;
  --accent: #5ec2ff;
  --primary: #ffd23f;
  --on-primary: #0b1626;
  --ok: #3ddc84;
  --bad: #ff8585;
  --warn: #ffb347;
  --radius: 16px;
}

* { box-sizing: border-box; }
html { font-size: 20px; -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: system-ui, -apple-system, 'Segoe UI', Roboto, Arial, sans-serif;
  line-height: 1.55;
}
h1, h2, h3 { line-height: 1.2; margin: 0 0 .5em; }
h1 { font-size: 2rem; }
h2 { font-size: 1.55rem; }
h3 { font-size: 1.25rem; }
p { margin: 0 0 .8em; }
a { color: var(--accent); }
ul, ol { padding-left: 1.4em; margin: 0 0 .8em; }
li { margin-bottom: .45em; }
b { color: #fff; }

.skip { position: absolute; left: -999px; top: 0; background: var(--primary); color: var(--on-primary); padding: 12px 18px; font-weight: 700; z-index: 20; }
.skip:focus { left: 8px; top: 8px; }

/* ---------- Foco grande (teclado / control remoto) ---------- */
a, button, input, select, [tabindex] { scroll-margin: 150px 0 110px; }
:focus { outline: none; }
:focus-visible,
.btn:focus, .card:focus, .opt:focus, input:focus {
  outline: 6px solid #fff;
  outline-offset: 4px;
  box-shadow: 0 0 0 4px #0b1626, 0 0 0 12px rgba(255, 210, 63, .85);
  position: relative;
  z-index: 2;
}
main:focus { outline: none; box-shadow: none; }

/* ---------- Barra superior ---------- */
#top {
  position: sticky; top: 0; z-index: 10;
  background: #08111e;
  border-bottom: 3px solid var(--line);
  padding: 10px 16px 12px;
}
.top-inner { max-width: 1100px; margin: 0 auto; }
.bar-row { display: flex; flex-wrap: wrap; align-items: center; gap: 10px 14px; justify-content: space-between; }
.brand { font-size: 1.35rem; font-weight: 800; color: #fff; text-decoration: none; padding: 6px 4px; }
.brand span { color: var(--primary); }
nav { display: flex; flex-wrap: wrap; gap: 10px; }
.global { display: flex; align-items: center; gap: 14px; margin-top: 8px; }
.glabel { font-weight: 700; font-size: 1rem; white-space: nowrap; }
.gtrack { flex: 1; height: 28px; background: #223654; border: 3px solid var(--line); border-radius: 999px; overflow: hidden; }
.gfill { height: 100%; width: 0; background: linear-gradient(90deg, var(--accent), var(--ok)); transition: width .5s ease; }
.gpct { font-size: 1.5rem; font-weight: 800; min-width: 3.4ch; text-align: right; }

/* ---------- Botones ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  min-height: 56px; padding: 8px 22px;
  font: inherit; font-size: 1.05rem; font-weight: 700; text-decoration: none; text-align: center;
  color: var(--text); background: var(--card2);
  border: 3px solid var(--line); border-radius: 14px;
  cursor: pointer;
}
.btn:hover { background: #26416a; }
.btn[aria-current='page'], .btn.on { background: #2b4f82; border-color: var(--accent); }
.btn-primary { background: var(--primary); color: var(--on-primary); border-color: var(--primary); }
.btn-primary:hover { background: #ffe07a; }
.btn-ok { background: var(--ok); color: #05210f; border-color: var(--ok); }
.btn-danger { background: #3a1a22; border-color: var(--bad); color: #ffd7d7; }
.btn[disabled] { opacity: .45; cursor: not-allowed; }
.btn-big { min-height: 66px; font-size: 1.2rem; padding: 10px 28px; }
.btn-sq { min-width: 56px; padding: 8px 10px; font-size: 1.4rem; }
.row { display: flex; flex-wrap: wrap; gap: 12px; align-items: center; }
.row.gap-lg { gap: 18px; }

/* ---------- Contenido ---------- */
main { max-width: 1100px; margin: 0 auto; padding: 22px 16px 80px; }
.lead { font-size: 1.15rem; color: var(--muted); }
.muted { color: var(--muted); }
.crumb { margin-bottom: 10px; }

.card {
  display: block; background: var(--card); border: 3px solid var(--line); border-radius: var(--radius);
  padding: 18px 20px; color: var(--text); text-decoration: none;
}
a.card { cursor: pointer; }
a.card:hover { background: var(--card2); border-color: var(--accent); }
.grid { display: grid; gap: 16px; grid-template-columns: repeat(auto-fill, minmax(290px, 1fr)); }

.hero { background: linear-gradient(135deg, #17325a, #0f2038); border: 3px solid var(--line); border-radius: var(--radius); padding: 22px 22px 18px; margin-bottom: 22px; }
.hero h1 { margin-bottom: .25em; }

.topic { display: flex; flex-direction: column; gap: 8px; min-height: 230px; }
.topic .glyph { font-family: Consolas, 'Courier New', monospace; font-size: 1.05rem; color: var(--primary); font-weight: 700; }
.topic h3 { margin: 0; font-size: 1.3rem; }
.topic .pct { font-size: 2.4rem; font-weight: 800; line-height: 1; }
.badge { display: inline-block; align-self: flex-start; font-weight: 800; font-size: 1rem; padding: 3px 14px; border-radius: 999px; border: 3px solid; }
.badge.sin { color: #dbe4f1; border-color: #8aa0bf; }
.badge.practica { color: var(--accent); border-color: var(--accent); }
.badge.dominado { color: #04230f; background: var(--ok); border-color: var(--ok); }
.mini { height: 16px; background: #223654; border: 2px solid var(--line); border-radius: 999px; overflow: hidden; }
.mini > div { height: 100%; background: var(--accent); }
.dominado-card .mini > div { background: var(--ok); }
.stats { display: flex; gap: 18px; font-weight: 700; margin-top: auto; }
.stats .good { color: var(--ok); }
.stats .badc { color: var(--bad); }
.tap { color: var(--primary); font-weight: 700; }

.callout { background: #3a2f10; border: 3px solid var(--primary); border-radius: var(--radius); padding: 14px 18px; margin: 16px 0; }
.callout.blue { background: #10304a; border-color: var(--accent); }
.callout.red { background: #3b1620; border-color: var(--bad); }

/* ---------- Lección ---------- */
.tabs { display: flex; flex-wrap: wrap; gap: 10px; margin: 8px 0 20px; }
.lesson section { background: var(--card); border: 3px solid var(--line); border-radius: var(--radius); padding: 16px 22px 10px; margin-bottom: 18px; }
.example { background: var(--card2); border-left: 8px solid var(--primary); border-radius: 12px; padding: 12px 18px 6px; margin-bottom: 14px; }
.example .q { font-size: 1.2rem; font-weight: 800; margin-bottom: .4em; }
.example .res { font-weight: 800; color: var(--ok); font-size: 1.15rem; }

/* ---------- Ejercicios ---------- */
.levels { display: flex; flex-wrap: wrap; gap: 10px; margin-bottom: 16px; }
.ex { background: var(--card); border: 3px solid var(--line); border-radius: var(--radius); padding: 20px 22px; }
.ex .text { font-size: 1.25rem; margin-bottom: .5em; }
.math { font-size: 1.8rem; font-weight: 700; color: var(--primary); margin: 6px 0 16px; overflow-wrap: anywhere; font-family: Cambria, 'Cambria Math', Georgia, serif; }
.field { display: flex; flex-wrap: wrap; align-items: center; gap: 10px 14px; margin-bottom: 12px; }
.field label { font-weight: 700; font-size: 1.15rem; min-width: 9ch; }
input.ans {
  font: inherit; font-size: 1.5rem; font-weight: 700; color: #fff; background: #0b1626;
  border: 3px solid var(--accent); border-radius: 12px; padding: 8px 16px; min-height: 60px;
  width: min(100%, 440px);
}
.pad { display: flex; flex-wrap: wrap; gap: 8px; margin: 4px 0 14px; }
.pad .btn { min-height: 52px; min-width: 52px; padding: 4px 12px; font-size: 1.25rem; }
.help { color: var(--muted); font-size: .95rem; margin: -4px 0 14px; }
.options { display: grid; gap: 12px; margin-bottom: 14px; }
.opt {
  display: flex; gap: 14px; align-items: center; text-align: left; width: 100%;
  min-height: 64px; padding: 10px 18px; font: inherit; font-size: 1.35rem; font-weight: 700;
  color: #fff; background: var(--card2); border: 3px solid var(--line); border-radius: 14px; cursor: pointer;
}
.opt:hover { border-color: var(--accent); }
.opt .mk { min-width: 1.6em; font-size: 1.4rem; }
.opt.sel { border-color: var(--primary); background: #3a2f10; }
.opt.right { border-color: var(--ok); background: #0f3a22; }
.opt.wrong { border-color: var(--bad); background: #3b1620; }
.actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 8px; }
.fb { margin-top: 18px; border: 3px solid; border-radius: var(--radius); padding: 14px 20px 8px; }
.fb.ok { border-color: var(--ok); background: #0e2e1d; }
.fb.bad { border-color: var(--bad); background: #331721; }
.fb.warn { border-color: var(--warn); background: #382a0d; }
.fb h3 { margin-bottom: .3em; }
.fb ol li { margin-bottom: .6em; }
.errbox { background: rgba(0, 0, 0, .3); border-left: 8px solid var(--warn); padding: 10px 16px; border-radius: 10px; margin: 8px 0 12px; }
.hintbox { background: #10304a; border-left: 8px solid var(--accent); padding: 10px 16px; border-radius: 10px; margin: 12px 0; }
.streak { font-weight: 800; color: var(--primary); }
.topic-head { display: flex; flex-wrap: wrap; align-items: center; gap: 14px 26px; margin-bottom: 14px; }
.topic-head .stat { font-weight: 800; font-size: 1.15rem; }

/* ---------- Gráficos ---------- */
.lab { display: grid; gap: 20px; grid-template-columns: minmax(300px, 640px) 1fr; align-items: start; }
@media (max-width: 960px) { .lab { grid-template-columns: 1fr; } }
canvas.plot { width: 100%; aspect-ratio: 1 / 1; max-width: 640px; display: block; border: 3px solid var(--line); border-radius: var(--radius); background: #0b1626; }
.ex canvas.plot { margin: 6px 0 16px; max-width: 520px; }
.slider { background: var(--card); border: 3px solid var(--line); border-radius: var(--radius); padding: 10px 16px 14px; margin-bottom: 12px; }
.slider .head { display: flex; justify-content: space-between; align-items: center; font-weight: 800; font-size: 1.2rem; margin-bottom: 6px; gap: 10px; }
.slider .val { color: var(--primary); font-size: 1.5rem; }
.slider .ctl { display: flex; gap: 10px; align-items: center; }
input[type='range'] { flex: 1; min-width: 0; height: 44px; background: transparent; accent-color: var(--primary); cursor: pointer; }
input[type='range']::-webkit-slider-runnable-track { height: 14px; background: #3a5784; border-radius: 999px; }
input[type='range']::-webkit-slider-thumb { -webkit-appearance: none; width: 38px; height: 38px; margin-top: -12px; border-radius: 50%; background: var(--primary); border: 4px solid #0b1626; }
input[type='range']::-moz-range-track { height: 14px; background: #3a5784; border-radius: 999px; }
input[type='range']::-moz-range-thumb { width: 30px; height: 30px; border-radius: 50%; background: var(--primary); border: 4px solid #0b1626; }
.info { background: var(--card); border: 3px solid var(--line); border-radius: var(--radius); padding: 14px 20px 6px; }
.info .eq { font-size: 1.6rem; font-weight: 800; color: var(--primary); font-family: Cambria, 'Cambria Math', Georgia, serif; margin-bottom: 8px; overflow-wrap: anywhere; }
.info li { font-size: 1.05rem; }

/* ---------- Simulacro ---------- */
.simbar { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 10px; margin-bottom: 14px; }
.dots { display: flex; gap: 8px; flex-wrap: wrap; }
.dot { width: 26px; height: 26px; border-radius: 50%; border: 3px solid var(--line); background: #223654; }
.dot.done { background: var(--accent); border-color: var(--accent); }
.dot.now { border-color: #fff; background: var(--primary); }
.score { font-size: 3rem; font-weight: 800; line-height: 1.1; }
.nota { font-size: 4rem; font-weight: 800; color: var(--primary); line-height: 1; }
.review { margin-top: 16px; }
.review details { background: var(--card); border: 3px solid var(--line); border-radius: 14px; margin-bottom: 12px; padding: 4px 16px; }
.review summary { cursor: pointer; font-size: 1.1rem; font-weight: 700; padding: 10px 0; min-height: 52px; }
.review details.ok { border-color: var(--ok); }
.review details.bad { border-color: var(--bad); }
.hist li { font-size: 1.05rem; }

.sr { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); }

@media (max-width: 560px) {
  html { font-size: 19px; }
  h1 { font-size: 1.65rem; }
  .glabel { display: none; }
  .btn { padding: 8px 16px; }
  .math { font-size: 1.5rem; }
}
@media (prefers-reduced-motion: reduce) { .gfill { transition: none; } }