:root{
  --bg:#f5f7fb;--panel:#ffffff;--ink:#111827;--muted:#6b7280;
  --accent:#2563eb;--accent-2:#1d4ed8;--border:#d1d5db;--soft:#eef2f7;
  --shadow:0 6px 18px rgba(0,0,0,.08);--radius:12px;--radius-sm:8px;--gap:10px;
  --footer-h:74px;
}
*{box-sizing:border-box}
html,body{height:100%}
body{
  margin:0;padding:0;
  background:linear-gradient(180deg,var(--bg),#ffffff);
  color:var(--ink);
  font-family:system-ui,-apple-system,"Segoe UI",Roboto,Arial,sans-serif;
  -webkit-font-smoothing:antialiased;
  min-height:100vh;display:flex;flex-direction:column;
}
a{color:var(--accent);text-decoration:none}
a:hover{text-decoration:underline}
h1,h2,h3,h4,p{margin:0}

/* ── BARRA SUPERIOR ── */
#tituloinicial{
  position:sticky;top:0;z-index:10;
  background:var(--panel);border-bottom:1px solid var(--border);
  box-shadow:0 2px 10px rgba(0,0,0,.04);
  display:flex;align-items:center;justify-content:space-between;
  gap:24px;padding:14px 18px;flex-shrink:0;
}
#tituloinicial h1{
  font-size:18px;font-weight:800;letter-spacing:.2px;line-height:1.2;
  flex:1;text-align:center;
}
#controlesTop{display:flex;align-items:center;gap:14px}
.abreVentana{
  display:inline-flex;align-items:center;
  font-size:14px;font-weight:700;padding:8px 10px;
  border-radius:var(--radius-sm);background:var(--soft);
  border:1px solid var(--border);color:var(--accent);
  cursor:pointer;white-space:nowrap;
}
.abreVentana:hover{background:#e9eef9;text-decoration:none}
#btnHome{
  display:inline-flex;flex-direction:column;align-items:center;justify-content:center;
  width:46px;height:50px;background:var(--soft);border:1px solid var(--border);
  border-radius:10px;gap:2px;transition:.15s transform,.15s background;
  text-decoration:none;
}
#btnHome:hover{transform:translateY(-1px);background:#e9eef9;text-decoration:none}
#btnHome svg{display:block;fill:var(--ink)}
#btnHome span{font-size:9px;line-height:9px;color:var(--ink);font-weight:800;letter-spacing:.5px}

/* ── CONTENEDOR PRINCIPAL ── */
#contenedor{
  height:calc(100vh - 76px - var(--footer-h));
  width:100%;padding:var(--gap);
  display:flex;flex-direction:column;gap:var(--gap);flex:1;
}

/* ── PANEL DE ENTRADA ── */
#caja1{
  background:var(--panel);border:1px solid var(--border);
  border-radius:var(--radius);box-shadow:var(--shadow);
  padding:14px 18px;flex:0 0 auto;overflow-y:auto;max-height:52vh;
}
#tituloCaja1{
  display:flex;align-items:center;justify-content:space-between;
  font-size:12px;font-weight:800;letter-spacing:.5px;text-transform:uppercase;
  color:var(--muted);padding-bottom:8px;border-bottom:1px dashed var(--border);margin-bottom:12px;
}

/* ── ESPACIO DE TRABAJO ── */
#caja2borde{background:transparent;flex:1;min-height:200px;display:flex;overflow:hidden;}
#caja2{
  flex:1;background:var(--panel);border:1px solid var(--border);
  border-radius:var(--radius);box-shadow:var(--shadow);
  padding:10px;display:flex;flex-direction:column;overflow:hidden;
}
h4{
  font-size:12px;font-weight:900;color:var(--muted);
  letter-spacing:.6px;text-transform:uppercase;margin:0 0 6px;
  display:block;flex-shrink:0;
}
#caja21{
  flex:1;overflow-y:auto;overflow-x:auto;padding:6px;
  border:1px solid var(--border);border-radius:var(--radius-sm);
  background:#fafafe;min-height:0;
}

/* ── TARJETAS DE RESOLUCIÓN ── */
.stepCard{
  margin:8px 0;padding:14px 16px;
  border:1px solid var(--border);border-radius:10px;
  background:#fff;overflow-x:auto;
}
.stepCard .stepTitle{
  font-size:11px;font-weight:800;color:#2d4faa;
  text-transform:uppercase;letter-spacing:.07em;margin-bottom:10px;
}
.stepCard.resultCard{background:#f0f4ff;border-color:rgba(59,110,248,.3);}
.stepCard.resultCard .stepTitle{color:#1a2b6b;font-size:13px;}

/* ── FILAS DE MATRICES ── */
.matRow{display:flex;align-items:center;gap:10px;margin:6px 0;flex-wrap:wrap;}
.matLabel{font-weight:700;min-width:30px;font-size:14px;}
.matGroup{display:flex;align-items:center;gap:6px;}

/* ── FORMULARIOS E INPUTS ── */
label{margin-right:4px;font-size:12px;font-weight:700;color:var(--ink);}
table{border-collapse:separate;border-spacing:6px;font-size:14px;margin:0;padding:0}
td{text-align:right;padding:0 2px}
.inputCorto{
  height:30px;border:1px solid var(--border);border-radius:6px;
  padding:0 6px;background:var(--panel);color:var(--ink);
  outline:none;width:46px;text-align:center;font-weight:700;
}
.inputCorto:focus{border-color:var(--accent);box-shadow:0 0 0 3px rgba(37,99,235,.12)}
.inputEcuacion{
  height:34px;border:1px solid var(--border);border-radius:8px;
  padding:0 10px;background:var(--panel);color:var(--ink);
  outline:none;width:280px;font-size:15px;font-family:monospace;
}
.inputEcuacion:focus{border-color:var(--accent);box-shadow:0 0 0 3px rgba(37,99,235,.12)}
.inputPequeno{
  height:30px;border:1px solid var(--border);border-radius:6px;
  padding:0 8px;background:var(--panel);color:var(--ink);
  outline:none;width:56px;font-size:14px;font-weight:700;
}
.inputPequeno:focus{border-color:var(--accent);box-shadow:0 0 0 3px rgba(37,99,235,.12)}

/* ── BOTONES ── */
button{
  appearance:none;border:1px solid var(--border);background:var(--soft);
  padding:7px 10px;border-radius:8px;font-weight:800;font-size:12px;
  cursor:pointer;transition:.12s transform,.12s background,.12s border-color;
  display:inline-flex;align-items:center;justify-content:center;
}
button:hover{transform:translateY(-1px);background:#e9eef9;border-color:#c7d2fe}
button:active{transform:translateY(0)}
button.primary{background:var(--accent);color:#fff;border-color:var(--accent)}
button.primary:hover{background:var(--accent-2);border-color:var(--accent-2)}

/* ── INDICADOR DE FASE ── */
.fase{
  background:var(--soft);border:1px dashed var(--border);border-radius:8px;
  padding:8px 12px;font-size:13px;color:var(--muted);margin:8px 0;
}
.fase strong{color:var(--ink)}

/* ── BLOQUE DE ENTRADA DE MATRIZ ── */
.matrizInputWrap{
  margin:10px 0 14px;padding:10px 12px;
  background:#fafafe;border:1px solid var(--border);border-radius:10px;
}
.matrizInputWrap .matNombreLabel{
  font-weight:700;font-size:14px;margin-bottom:6px;display:block;color:var(--ink);
}

/* ── MENSAJES ── */
.msgError{color:#dc2626;font-size:12px;font-weight:700;margin-top:6px;}
.msgOk{color:#16a34a;font-size:12px;font-weight:700;margin-top:6px;}

/* ── MODAL ── */
.ventana{
  display:none;position:fixed;inset:0;
  background-color:rgba(2,6,23,.55);
  justify-content:center;align-items:center;
  z-index:1000;padding:18px;
}
.contenidoVentana{
  background:var(--panel);padding:18px;border-radius:var(--radius);
  width:min(900px,94vw);text-align:center;position:relative;
  z-index:1001;border:1px solid var(--border);box-shadow:var(--shadow);
}
.cierraVentana{position:absolute;top:10px;right:12px;font-size:22px;cursor:pointer;color:var(--muted);}
.cierraVentana:hover{color:var(--ink)}
iframe{border:none;border-radius:10px}

/* ── FOOTER ── */
.siteFooter{background:var(--panel);border-top:1px solid var(--border);padding:14px 24px;flex-shrink:0;}
.footerInner{display:flex;gap:18px;justify-content:center;flex-wrap:wrap;}
.footerInner a{font-size:12px;color:var(--muted);text-decoration:none}
.footerInner a:hover{color:var(--accent)}

/* ── KATEX ── */
#calculadora .katex{font-size:16px}

/* ── RESPONSIVE ── */
@media(max-width:700px){
  #tituloinicial{flex-wrap:wrap;gap:10px;padding:10px 12px;}
  #controlesTop{gap:8px;flex-wrap:wrap;justify-content:flex-end;}
  #tituloinicial h1{font-size:14px;flex-basis:100%;text-align:left;}
  .inputEcuacion{width:200px}
  #caja1{max-height:55vh}
}
@media(max-width:480px){
  #tituloinicial h1{font-size:13px}
  .abreVentana{font-size:12px;padding:6px 8px}
  #caja1{max-height:60vh}
}