/* =========================================================
   Catálogo de Álgebra Lineal — hoja de estilos
   Paleta: papel + tinta + acentos de latón y azul pizarra
   ========================================================= */

:root{
  --paper: #000000;
  --paper-raised: #0D1116;
  --ink: #F2F5F7;
  --ink-soft: #A3AEB8;
  --rule: #2A3540;
  --rule-soft: #0F1A24;
  --brass: #5cc9ff;
  --brass-dim: #5dfcef;
  --slate: #A9C8E8;
  --slate-dim: #6F8FA8;
  --tag-verde: #A8DCC0;
  --tag-verde-bg: #14251D;
  --tag-ambar-bg: #1B2A22;
  --tag-azul-bg: #13222F;

  --serif: "Source Serif 4", "Iowan Old Style", "Georgia", serif;
  --sans: "IBM Plex Sans", "Segoe UI", sans-serif;
  --mono: "IBM Plex Mono", "SFMono-Regular", monospace;

  --maxw: 1120px;
}

@font-face{
  font-family: "Source Serif 4";
  src: local("Source Serif 4");
}

*, *::before, *::after{ box-sizing: border-box; }

html{ scroll-behavior: smooth; }

body{
  margin: 0;
  background-color: var(--paper);
  background-image:
    linear-gradient(var(--rule-soft) 1px, transparent 1px),
    linear-gradient(90deg, var(--rule-soft) 1px, transparent 1px);
  background-size: 28px 28px;
  background-position: -1px -1px;
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.6;
}

a{ color: var(--slate); text-decoration-thickness: 1px; text-underline-offset: 2px; }
a:hover{ color: var(--brass); }
a:focus-visible, button:focus-visible, .tarjeta:focus-visible{
  outline: 2px solid var(--brass);
  outline-offset: 3px;
}

.envoltura{
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 28px;
}

/* ---------- Encabezado ---------- */
.encabezado{
  border-bottom: 1px solid var(--rule);
  background: linear-gradient(180deg, var(--paper-raised), var(--paper) 90%);
  position: sticky;
  top: 0;
  z-index: 20;
  backdrop-filter: blur(2px);
}
.encabezado .envoltura{
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 8px 24px;
  padding-top: 18px;
  padding-bottom: 16px;
}
.marca{
  display: flex;
  align-items: baseline;
  gap: 10px;
  font-family: var(--serif);
}
.marca .corchete{
  font-family: var(--mono);
  color: var(--brass);
  font-size: 1.3rem;
}
.marca-texto{
  font-size: 1.15rem;
  font-weight: 600;
  letter-spacing: 0.01em;
}
.marca-sub{
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--ink-soft);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}
nav.navegacion{
  display: flex;
  gap: 22px;
  font-family: var(--mono);
  font-size: 0.82rem;
  letter-spacing: 0.02em;
}
nav.navegacion a{
  color: var(--ink);
  text-decoration: none;
  padding-bottom: 3px;
  border-bottom: 1px solid transparent;
}
nav.navegacion a:hover, nav.navegacion a[aria-current="page"]{
  color: var(--brass);
  border-bottom-color: var(--brass);
}

/* ---------- Héroe ---------- */
.heroe{
  padding: 56px 0 40px;
  border-bottom: 1px solid var(--rule);
}
.heroe .eyebrow{
  font-family: var(--mono);
  font-size: 0.78rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--slate);
  display: flex;
  align-items: center;
  gap: 10px;
}
.heroe .eyebrow::before{
  content: "";
  width: 26px;
  height: 1px;
  background: var(--slate-dim);
  display: inline-block;
}
.heroe h1{
  font-family: var(--serif);
  font-weight: 600;
  font-size: clamp(2rem, 4vw, 2.9rem);
  line-height: 1.15;
  margin: 14px 0 16px;
  max-width: 18ch;
}
.heroe p.desc{
  max-width: 62ch;
  color: var(--ink-soft);
  font-size: 1.02rem;
}

/* Matriz-resumen (signature element) */
.matriz-resumen{
  margin-top: 32px;
  display: flex;
  align-items: stretch;
  gap: 0;
  font-family: var(--mono);
}
.matriz-resumen .bracket-izq, .matriz-resumen .bracket-der{
  font-size: 3.4rem;
  color: var(--brass-dim);
  line-height: 1;
  align-self: stretch;
  display: flex;
  align-items: center;
  padding: 0 4px;
  user-select: none;
}
.matriz-grid{
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(130px, 1fr));
  gap: 1px;
  background: var(--rule);
  border: 1px solid var(--rule);
  flex: 1;
  max-width: 760px;
}
.matriz-celda{
  background: var(--paper-raised);
  padding: 12px 14px;
  display: flex;
  flex-direction: column;
  gap: 4px;
}
.matriz-celda .n{
  font-size: 1.4rem;
  color: var(--slate);
  font-weight: 600;
}
.matriz-celda .etiqueta{
  font-size: 0.68rem;
  color: var(--ink-soft);
  letter-spacing: 0.03em;
  text-transform: uppercase;
}

/* ---------- Secciones de categoría ---------- */
.categoria{
  padding: 46px 0;
  border-bottom: 1px solid var(--rule);
}
.categoria:last-of-type{ border-bottom: none; }

.categoria-titulo{
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin-bottom: 6px;
}
.categoria-titulo .corchete{
  font-family: var(--mono);
  color: var(--brass);
  font-size: 1.2rem;
}
.categoria-titulo h2{
  font-family: var(--serif);
  font-size: 1.5rem;
  font-weight: 600;
  margin: 0;
}
.categoria-prefijo{
  font-family: var(--mono);
  font-size: 0.75rem;
  color: var(--slate);
  letter-spacing: 0.05em;
}
.categoria-desc{
  color: var(--ink-soft);
  font-size: 0.95rem;
  max-width: 68ch;
  margin: 6px 0 24px;
}

.rejilla-tarjetas{
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 18px;
}

.tarjeta{
  background: var(--paper-raised);
  border: 1px solid var(--rule);
  padding: 18px 20px 20px;
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 10px;
  text-decoration: none;
  color: var(--ink);
  transition: border-color 0.15s ease, transform 0.15s ease;
}
.tarjeta:hover{
  border-color: var(--brass-dim);
  transform: translateY(-2px);
}
.tarjeta::before{
  content: "";
  position: absolute;
  top: 0; right: 0;
  width: 0; height: 0;
  border-style: solid;
  border-width: 0 16px 16px 0;
  border-color: transparent var(--rule) transparent transparent;
}
.tarjeta-cabeza{
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 10px;
}
.tarjeta-num{
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--brass);
  letter-spacing: 0.04em;
}
.tarjeta h3{
  font-family: var(--serif);
  font-size: 1.12rem;
  font-weight: 600;
  margin: 2px 0 0;
  line-height: 1.3;
}
.tarjeta p{
  font-size: 0.9rem;
  color: var(--ink-soft);
  margin: 0;
  flex: 1;
}
.etiquetas{
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 4px;
}
.etiqueta-pill{
  font-family: var(--mono);
  font-size: 0.68rem;
  padding: 2px 8px;
  border-radius: 2px;
  background: var(--tag-azul-bg);
  color: var(--slate);
  letter-spacing: 0.02em;
}
.estado{
  font-family: var(--mono);
  font-size: 0.68rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  padding-top: 8px;
  border-top: 1px dashed var(--rule);
  margin-top: 4px;
  color: var(--ink-soft);
}
.estado[data-estado="completa"]{ color: var(--tag-verde); }
.estado[data-estado="en-progreso"]{ color: var(--brass); }
.estado[data-estado="planeada"]{ color: var(--slate-dim); }

/* ---------- Notas / recursos (página 2) ---------- */
.curso{
  padding: 40px 0;
  border-bottom: 1px solid var(--rule);
}
.curso:last-of-type{ border-bottom: none; }
.curso-cabeza{
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 8px 20px;
  margin-bottom: 18px;
}
.curso-cabeza h2{
  font-family: var(--serif);
  font-size: 1.4rem;
  margin: 0;
  display: flex;
  align-items: baseline;
  gap: 10px;
}
.curso-cabeza h2 .corchete{ color: var(--brass); font-family: var(--mono); }
.horario{
  font-family: var(--mono);
  font-size: 0.78rem;
  color: var(--slate);
  background: var(--tag-azul-bg);
  padding: 3px 10px;
}
.curso-columnas{
  display: grid;
  grid-template-columns: 1.1fr 1fr;
  gap: 28px;
}
@media (max-width: 720px){
  .curso-columnas{ grid-template-columns: 1fr; }
}
.curso-bloque h3{
  font-family: var(--mono);
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--ink-soft);
  margin: 0 0 10px;
}
.lista-notas, .lista-recursos{
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.lista-notas li, .lista-recursos li{
  border-bottom: 1px dotted var(--rule);
  padding-bottom: 8px;
  font-size: 0.92rem;
}
.lista-notas a, .lista-recursos a{ text-decoration: none; }
.lista-notas a:hover, .lista-recursos a:hover{ text-decoration: underline; }
.recurso-tipo{
  font-family: var(--mono);
  font-size: 0.68rem;
  color: var(--slate-dim);
  margin-right: 6px;
}
.vacio{
  font-size: 0.88rem;
  color: var(--ink-soft);
  font-style: italic;
}

.paralela{
  padding: 40px 0 60px;
}
.paralela h2{
  font-family: var(--serif);
  font-size: 1.4rem;
  display: flex;
  gap: 10px;
  align-items: baseline;
}
.paralela h2 .corchete{ color: var(--brass); font-family: var(--mono); }
.paralela-desc{ color: var(--ink-soft); max-width: 68ch; margin: 6px 0 22px; }
.chips{ display: flex; flex-wrap: wrap; gap: 10px; }
.chip{
  font-family: var(--mono);
  font-size: 0.82rem;
  border: 1px solid var(--rule);
  background: var(--paper-raised);
  padding: 6px 14px;
  color: var(--ink);
}

/* ---------- Pie ---------- */
footer.pie{
  border-top: 1px solid var(--rule);
  padding: 26px 0 40px;
  font-family: var(--mono);
  font-size: 0.76rem;
  color: var(--ink-soft);
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 8px 20px;
}

@media (max-width: 640px){
  .heroe{ padding: 40px 0 32px; }
  .matriz-resumen .bracket-izq, .matriz-resumen .bracket-der{ font-size: 2.2rem; }
}