:root{
  --bg:#f4f7fb; --card:#ffffff; --ink:#1f2937; --muted:#6b7280;
  --accent:#2563eb; --accent-dark:#1d4ed8; --line:#e5e7eb;
  --radius:16px; --shadow:0 8px 24px rgba(31,41,55,.08);
  /* colores por materia */
  --mate:#2563eb; --espanol:#db2777; --sociales:#16a34a;
}
*{box-sizing:border-box}
body{
  margin:0;font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
  background:var(--bg);color:var(--ink);line-height:1.5;
  padding:22px 14px 60px;min-height:100vh;
}
.wrap{max-width:820px;margin:0 auto}

/* Header */
header.top{
  background:linear-gradient(135deg,var(--accent),var(--accent-dark));
  color:#fff;border-radius:var(--radius);padding:22px 24px;
  box-shadow:0 6px 20px rgba(37,99,235,.25);
}
header.top.mate{background:linear-gradient(135deg,#2563eb,#1d4ed8);box-shadow:0 6px 20px rgba(37,99,235,.25)}
header.top.espanol{background:linear-gradient(135deg,#db2777,#9d174d);box-shadow:0 6px 20px rgba(219,39,119,.25)}
header.top.sociales{background:linear-gradient(135deg,#16a34a,#166534);box-shadow:0 6px 20px rgba(22,163,74,.25)}
header.top h1{margin:0 0 4px;font-size:1.5rem}
header.top p{margin:0;opacity:.92;font-size:.95rem}
.back{
  display:inline-block;margin-bottom:12px;color:#fff;text-decoration:none;
  font-size:.9rem;font-weight:600;opacity:.92;
}
.back:hover{opacity:1;text-decoration:underline}

/* Grid de materias */
.subjects{
  display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));
  gap:16px;margin-top:22px;
}
.subject-card{
  display:flex;flex-direction:column;gap:6px;
  background:var(--card);border:1px solid var(--line);border-left:6px solid var(--accent);
  border-radius:var(--radius);padding:20px;text-decoration:none;color:inherit;
  box-shadow:var(--shadow);transition:transform .12s ease,box-shadow .12s ease;
  position:relative;
}
.subject-card:hover{transform:translateY(-3px);box-shadow:0 12px 28px rgba(31,41,55,.14)}
.subject-card[data-m="mate"]{border-left-color:var(--mate)}
.subject-card[data-m="espanol"]{border-left-color:var(--espanol)}
.subject-card[data-m="sociales"]{border-left-color:var(--sociales)}
.subject-card .icon{font-size:2.2rem;line-height:1}
.subject-card .name{font-size:1.15rem;font-weight:700}
.subject-card .desc{font-size:.9rem;color:var(--muted)}
.subject-card .go{margin-top:6px;font-weight:600;font-size:.9rem}
.subject-card[data-m="mate"] .go{color:var(--mate)}
.subject-card[data-m="espanol"] .go{color:var(--espanol)}
.subject-card[data-m="sociales"] .go{color:var(--sociales)}
.badge-soon{
  position:absolute;top:14px;right:14px;background:#f3f4f6;color:var(--muted);
  font-size:.7rem;font-weight:700;border-radius:999px;padding:3px 9px;text-transform:uppercase;letter-spacing:.04em;
}

/* Recursos dentro de una materia */
.resources{display:flex;flex-direction:column;gap:12px;margin-top:22px}
.resource-card{
  display:flex;align-items:center;gap:14px;
  background:var(--card);border:1px solid var(--line);border-radius:14px;padding:16px 18px;
  text-decoration:none;color:inherit;box-shadow:var(--shadow);
  transition:transform .12s ease,box-shadow .12s ease;
}
.resource-card:hover{transform:translateY(-2px);box-shadow:0 12px 28px rgba(31,41,55,.14)}
.resource-card .r-icon{font-size:1.8rem}
.resource-card .r-body{flex:1}
.resource-card .r-title{font-weight:700;font-size:1.02rem}
.resource-card .r-desc{font-size:.88rem;color:var(--muted)}
.resource-card .r-arrow{color:var(--accent);font-size:1.3rem;font-weight:700}

/* Placeholder "en construcción" */
.placeholder{
  background:var(--card);border:1px dashed var(--line);border-radius:var(--radius);
  padding:48px 24px;text-align:center;margin-top:22px;box-shadow:var(--shadow);
}
.placeholder .big{font-size:3rem;margin-bottom:8px}
.placeholder h2{margin:0 0 6px;font-size:1.25rem}
.placeholder p{margin:0;color:var(--muted);max-width:420px;margin:0 auto}

footer{text-align:center;color:var(--muted);font-size:.82rem;margin-top:32px}

/* Preparación de examen — Temas de Estudio + Recursos (reutilizable por materia) */
.exam-prep{
  background:var(--card);border:1px solid var(--line);border-radius:var(--radius);
  padding:20px 22px;margin-top:22px;box-shadow:var(--shadow);
}
.exam-prep .exam-head{display:flex;align-items:center;gap:14px}
.exam-prep .exam-icon{font-size:2rem;line-height:1}
.exam-prep .exam-head h2{margin:0;font-size:1.2rem}
.exam-prep .exam-date{margin:3px 0 0;color:var(--muted);font-size:.9rem;font-weight:600}
.exam-meta{display:flex;flex-direction:column;gap:5px;margin-top:14px;font-size:.9rem;color:var(--muted)}
.exam-meta strong{color:var(--ink);font-weight:600}
.exam-meta em{font-style:italic}
.study-section{margin-top:18px;padding-top:16px;border-top:1px solid var(--line)}
.study-section h3{margin:0 0 10px;font-size:1rem;display:flex;align-items:center;gap:8px}
.study-list{margin:0;padding:0;list-style:none;display:flex;flex-direction:column;gap:8px}
.study-list > li{
  position:relative;padding:10px 12px 10px 38px;background:var(--bg);
  border-radius:10px;font-size:.95rem;
}
.study-list > li::before{content:"📌";position:absolute;left:12px;top:10px;font-size:.95rem}
.study-list.refs > li::before{content:"📚"}
.topic-title{font-weight:600}
.subtopics{margin:8px 0 0;padding:0;list-style:none;display:flex;flex-direction:column;gap:4px}
.subtopics li{position:relative;padding-left:18px;font-size:.9rem;color:var(--muted)}
.subtopics li::before{content:"–";position:absolute;left:5px;color:var(--muted)}
.study-list em{font-style:italic}

/* Apuntes (contenido renderizado tipo "prose") */
.prose{
  background:var(--card);border:1px solid var(--line);border-radius:var(--radius);
  padding:24px 26px;margin-top:22px;box-shadow:var(--shadow);
}
.prose h1{font-size:1.4rem;margin:0 0 4px}
.prose h2{font-size:1.2rem;margin:26px 0 10px;padding-bottom:6px;border-bottom:2px solid var(--line)}
.prose h3{font-size:1.05rem;margin:20px 0 8px}
.prose h4{font-size:.98rem;margin:16px 0 6px;color:var(--accent)}
.prose p{margin:10px 0}
.prose ul,.prose ol{margin:10px 0;padding-left:22px}
.prose li{margin:5px 0}
.prose strong{font-weight:700}
.prose em{font-style:italic}
.prose hr{border:none;border-top:1px solid var(--line);margin:22px 0}
.prose blockquote{
  margin:14px 0;padding:10px 16px;background:var(--accent-soft,#eef2ff);
  border-left:4px solid var(--accent);border-radius:8px;color:#1e3a8a;
}
.prose blockquote p{margin:4px 0}
.prose code{
  font-family:"SFMono-Regular",Consolas,Menlo,monospace;font-size:.88em;
  background:#f3f4f6;padding:1px 6px;border-radius:6px;
}
.prose pre{
  background:#0f172a;color:#e2e8f0;padding:14px 16px;border-radius:10px;
  overflow:auto;font-size:.86rem;line-height:1.5;
}
.prose pre code{background:none;color:inherit;padding:0}
.table-wrap{overflow-x:auto;margin:14px 0}
.prose table{border-collapse:collapse;width:100%;font-size:.92rem;min-width:420px}
.prose th,.prose td{border:1px solid var(--line);padding:8px 11px;text-align:left;vertical-align:top}
.prose thead th{background:var(--accent);color:#fff;font-weight:600}
.prose tbody tr:nth-child(even){background:var(--bg)}
.prose td.center,.prose th.center{text-align:center}

/* ── Componentes visuales para apuntes de Matemáticas (reemplazan diagramas ASCII) ── */

/* Fórmula destacada (centrada, en vez de <pre> oscuro tipo código) */
.prose .eq{margin:14px 0;padding:12px 18px;background:#eef2ff;border:1px solid #dbe3ff;border-radius:10px;text-align:center;font-size:1.2rem;line-height:1.7;color:#1e3a8a;font-variant-numeric:tabular-nums}
.prose .by{color:var(--muted);font-size:.85rem}

/* Cálculo paso a paso (claro, no "código") */
.prose .calc{margin:14px 0;padding:12px 16px;background:#f8fafc;border-left:4px solid var(--accent);border-radius:8px;font-family:"SFMono-Regular",Consolas,Menlo,monospace;font-size:.98rem;line-height:1.8;color:var(--ink)}

/* Recta numérica */
.prose .numline{display:flex;justify-content:center;flex-wrap:nowrap;overflow-x:auto;margin:18px 0 6px;padding:6px 0}
.prose .numline .nl{position:relative;min-width:42px;text-align:center;padding-top:22px;font-size:.95rem;font-variant-numeric:tabular-nums;color:var(--ink)}
.prose .numline .nl::before{content:"";position:absolute;top:10px;left:0;right:0;height:2px;background:#cbd5e1}
.prose .numline .nl:first-child::before{left:50%}
.prose .numline .nl:last-child::before{right:50%}
.prose .numline .nl::after{content:"";position:absolute;top:6px;left:50%;width:2px;height:9px;background:#94a3b8;transform:translateX(-50%)}
.prose .numline .nl.mark{font-weight:700;color:var(--accent)}
.prose .numline .nl.mark::after{background:var(--accent);height:14px;top:3px}
.prose .numline .nl.dot::after{width:11px;height:11px;border-radius:50%;background:var(--accent);top:5px}
.prose .nl-note{text-align:center;color:var(--muted);font-size:.85rem;margin:0 0 14px}

/* Escalera de factorización prima */
.prose .factor{border-collapse:collapse;width:auto;min-width:0;margin:14px auto;font-variant-numeric:tabular-nums}
.prose .factor td{border:none;padding:3px 18px;font-size:1.02rem}
.prose .factor td:first-child{text-align:right;border-right:2px solid var(--accent)}
.prose .factor td:last-child{text-align:left;color:var(--accent);font-weight:700}

/* Rejilla de reglas de signos */
.prose .signs{display:grid;grid-template-columns:1fr 1fr;gap:8px;max-width:360px;margin:14px 0;padding:0;list-style:none}
.prose .signs li{margin:0;background:#eef2ff;border-radius:8px;padding:9px 12px;text-align:center;font-size:1.05rem;color:#1e3a8a;font-variant-numeric:tabular-nums}
.prose .signs b{color:var(--accent)}

/* Anatomía de una expresión (partes de la raíz / la potencia) */
.prose .parts{margin:16px 0;padding:16px 18px;background:#f8fafc;border:1px solid var(--line);border-radius:12px}
.prose .parts .expr{font-size:2rem;text-align:center;margin:0 0 12px;line-height:1.1}
.prose .parts .p1{color:#d97706}
.prose .parts .p2{color:#2563eb}
.prose .parts .p3{color:#16a34a}
.prose .parts ul{list-style:none;padding:0;margin:0;display:flex;flex-direction:column;gap:6px}
.prose .parts li{margin:0;font-size:.92rem}
.prose .parts .sw{display:inline-block;width:13px;height:13px;border-radius:3px;margin-right:8px;vertical-align:-1px}
.prose .parts .sw1{background:#d97706}
.prose .parts .sw2{background:#2563eb}
.prose .parts .sw3{background:#16a34a}

/* Pirámide numérica */
.prose .pyramid{display:flex;flex-direction:column;align-items:center;gap:6px;margin:16px 0}
.prose .pyramid .row{display:flex;gap:6px}
.prose .pyramid .c{min-width:52px;padding:8px 6px;background:#eef2ff;border:1px solid #dbe3ff;border-radius:8px;text-align:center;font-weight:600;color:#1e3a8a;font-variant-numeric:tabular-nums}
.prose .pyramid .c.base{background:#dbeafe;border-color:#bfdbfe}

/* Título de sección dentro de una materia (ej. "Material de estudio") */
.section-title{margin:30px 0 0;font-size:1.1rem;display:flex;align-items:center;gap:8px}

/* Botón destacado de práctica interactiva */
.practica-cta{
  display:flex;align-items:center;gap:16px;margin-top:22px;
  background:linear-gradient(135deg,var(--espanol,#db2777),#9d174d);color:#fff;
  border-radius:var(--radius);padding:18px 20px;text-decoration:none;
  box-shadow:0 8px 24px rgba(219,39,119,.28);transition:transform .12s ease,box-shadow .12s ease;
}
.practica-cta:hover{transform:translateY(-3px);box-shadow:0 14px 30px rgba(219,39,119,.36)}
.practica-cta .pc-icon{font-size:2.2rem;line-height:1}
.practica-cta .pc-body{flex:1;display:flex;flex-direction:column;gap:3px}
.practica-cta .pc-title{font-size:1.15rem;font-weight:700}
.practica-cta .pc-desc{font-size:.9rem;opacity:.95}
.practica-cta .pc-desc strong{font-weight:700}
.practica-cta .pc-go{font-weight:700;white-space:nowrap}