:root {
  --bg: #f4f6fb;
  --card: #ffffff;
  --text: #0f172a;
  --muted: #526077;
  --border: #dde3ee;
  --primary: #1d4ed8;
  --primary-hover: #1e40af;
  --primary-soft: #e8efff;
  --on-primary: #ffffff;
  --ok: #15803d;
  --ok-bg: #e7f8ee;
  --bad: #c0262d;
  --bad-bg: #fdecec;
  --warn-bg: #fff7e0;
  --warn: #8a5a00;
  --shadow: 0 1px 2px rgba(15, 23, 42, .06), 0 6px 24px rgba(15, 23, 42, .06);
  color-scheme: light dark;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0b1120;
    --card: #131c31;
    --text: #e6eaf2;
    --muted: #9aa6bd;
    --border: #26324d;
    --primary: #4f8cff;
    --primary-hover: #6b9fff;
    --primary-soft: #1a2a4d;
    --on-primary: #0b1120;
    --ok: #4ade80;
    --ok-bg: #0d2e1d;
    --bad: #ff7b7b;
    --bad-bg: #3a1417;
    --warn-bg: #3a2c08;
    --warn: #f3c969;
    --shadow: 0 1px 2px rgba(0, 0, 0, .3), 0 6px 24px rgba(0, 0, 0, .25);
  }
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: "Inter", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  font-size: 17px;
  line-height: 1.55;
}
[hidden] { display: none !important; }

.contenedor { max-width: 640px; margin: 0 auto; padding: 20px 16px 48px; }
.cabecera { text-align: center; margin: 8px 0 20px; }
.cabecera .sello { font-size: 13px; font-weight: 600; letter-spacing: .06em; text-transform: uppercase; color: var(--primary); }
.cabecera h1 { font-size: 24px; line-height: 1.25; margin: 4px 0 0; }

.tarjeta {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 16px;
  box-shadow: var(--shadow);
  padding: 22px 20px;
}
.tarjeta + .tarjeta { margin-top: 16px; }
h2 { font-size: 21px; line-height: 1.3; margin: 0 0 12px; }
p { margin: 0 0 12px; }
.muted { color: var(--muted); }
.centro { text-align: center; }

ul.reglas { padding-left: 0; list-style: none; margin: 0 0 20px; }
ul.reglas li { padding: 8px 0 8px 32px; position: relative; border-bottom: 1px solid var(--border); }
ul.reglas li:last-child { border-bottom: 0; }
ul.reglas li::before {
  content: ""; position: absolute; left: 6px; top: 16px; width: 10px; height: 10px;
  border-radius: 50%; background: var(--primary);
}

label { display: block; font-weight: 600; margin: 14px 0 6px; }
.ayuda { font-size: 14px; color: var(--muted); margin-top: 4px; }
input[type="text"], input[type="password"], select {
  width: 100%; font: inherit; color: var(--text); background: var(--bg);
  border: 1.5px solid var(--border); border-radius: 12px; padding: 13px 14px; min-height: 50px;
}
input:focus, select:focus { outline: none; border-color: var(--primary); box-shadow: 0 0 0 3px var(--primary-soft); }

.boton {
  display: block; width: 100%; font: inherit; font-weight: 600; font-size: 17px;
  border: 0; border-radius: 12px; padding: 15px 18px; min-height: 54px; cursor: pointer;
  background: var(--primary); color: var(--on-primary); margin-top: 20px;
  transition: background .15s;
}
.boton:hover { background: var(--primary-hover); }
.boton:disabled { opacity: .6; cursor: progress; }
.boton.secundario { background: transparent; color: var(--primary); border: 1.5px solid var(--border); }
.boton.peligro { background: var(--bad); color: #fff; }

.mensaje-error {
  background: var(--bad-bg); color: var(--bad); border-radius: 10px;
  padding: 10px 14px; margin-top: 14px; font-size: 15px; font-weight: 500;
}

/* Progreso */
.progreso-info { display: flex; justify-content: space-between; align-items: baseline; gap: 12px; font-size: 15px; margin-bottom: 8px; }
.progreso-info strong { font-size: 16px; }
.aciertos { color: var(--ok); font-weight: 600; }
.barra { height: 8px; background: var(--border); border-radius: 99px; overflow: hidden; margin-bottom: 18px; }
.barra > div { height: 100%; background: var(--primary); border-radius: 99px; transition: width .3s ease; }

.etiqueta { display: inline-block; font-size: 13px; font-weight: 600; color: var(--primary); background: var(--primary-soft); padding: 3px 10px; border-radius: 99px; margin-bottom: 10px; }
.enunciado { font-size: 19px; font-weight: 600; line-height: 1.45; margin-bottom: 18px; }

.opciones { display: grid; gap: 10px; }
.opcion {
  display: flex; align-items: flex-start; gap: 12px; width: 100%; text-align: left;
  font: inherit; color: var(--text); background: var(--card);
  border: 1.5px solid var(--border); border-radius: 12px; padding: 14px; min-height: 56px; cursor: pointer;
  transition: border-color .15s, background .15s;
}
.opcion:hover:not(:disabled) { border-color: var(--primary); background: var(--primary-soft); }
.opcion:disabled { cursor: default; }
.opcion .letra {
  flex: none; width: 30px; height: 30px; border-radius: 50%; display: grid; place-items: center;
  font-weight: 700; font-size: 14px; background: var(--primary-soft); color: var(--primary);
}
.opcion.elegida { border-color: var(--primary); }
.opcion.correcta { border-color: var(--ok); background: var(--ok-bg); }
.opcion.correcta .letra { background: var(--ok); color: var(--card); }
.opcion.incorrecta { border-color: var(--bad); background: var(--bad-bg); }
.opcion.incorrecta .letra { background: var(--bad); color: var(--card); }
.opcion.apagada { opacity: .55; }

.retro { margin-top: 18px; border-radius: 12px; padding: 14px 16px; border-left: 5px solid; }
.retro.ok { background: var(--ok-bg); border-color: var(--ok); }
.retro.mal { background: var(--bad-bg); border-color: var(--bad); }
.retro .titulo { font-weight: 700; font-size: 18px; margin-bottom: 4px; }
.retro.ok .titulo { color: var(--ok); }
.retro.mal .titulo { color: var(--bad); }
.retro p:last-child { margin-bottom: 0; }

/* Resultado */
.nota { font-size: 64px; font-weight: 800; line-height: 1; color: var(--primary); margin: 10px 0 4px; }
.nota small { font-size: 28px; color: var(--muted); font-weight: 600; }
.datos { margin: 18px 0; border-top: 1px solid var(--border); }
.datos div { display: flex; justify-content: space-between; gap: 12px; padding: 10px 0; border-bottom: 1px solid var(--border); }
.datos dt { color: var(--muted); }
.datos dd { margin: 0; font-weight: 600; text-align: right; }
.registrada { display: inline-flex; align-items: center; gap: 8px; background: var(--ok-bg); color: var(--ok); font-weight: 600; padding: 10px 14px; border-radius: 10px; }

.cargando { text-align: center; padding: 40px 0; color: var(--muted); }
.spinner { width: 32px; height: 32px; border: 3px solid var(--border); border-top-color: var(--primary); border-radius: 50%; margin: 0 auto 12px; animation: girar .8s linear infinite; }
@keyframes girar { to { transform: rotate(360deg); } }

.icono-grande { font-size: 44px; line-height: 1; margin-bottom: 10px; }