:root {
  --bg: #f2f4f7;
  --card: #ffffff;
  --text: #17202b;
  --muted: #5b6573;
  --line: #dde2e8;
  --line-strong: #c3cad3;
  --accent: #1f4e79;
  --accent-hover: #183f63;
  --accent-ink: #ffffff;
  --accent-soft: #e6eef6;
  --warn: #9a5208;
  --warn-soft: #fcf0e1;
  --danger: #b3261e;
  --danger-soft: #fbe8e6;
  --ok: #1b7444;
  --ok-soft: #e2f3e9;
  --shadow: 0 1px 2px rgba(16, 24, 40, .06), 0 1px 3px rgba(16, 24, 40, .08);
  --radius: 12px;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f1419;
    --card: #182029;
    --text: #e6eaef;
    --muted: #9aa5b2;
    --line: #2a3440;
    --line-strong: #3b4756;
    --accent: #7fb0dd;
    --accent-hover: #9cc3e6;
    --accent-ink: #0d1a26;
    --accent-soft: #1d2d3d;
    --warn: #f0b066;
    --warn-soft: #3a2a17;
    --danger: #f2a49d;
    --danger-soft: #3b1e1c;
    --ok: #8fd4ad;
    --ok-soft: #1a3226;
    --shadow: none;
    color-scheme: dark;
  }
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.55 system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", sans-serif;
  -webkit-tap-highlight-color: transparent;
}
a { color: var(--accent); }
h1 { font-size: clamp(1.2rem, 1rem + 1vw, 1.6rem); line-height: 1.25; margin: 0 0 6px; }
h2 { font-size: 1.1rem; margin: 0 0 12px; }
h3 { font-size: 1rem; margin: 0 0 8px; }
p { margin: 0 0 10px; }
.muted { color: var(--muted); }
.small { font-size: .875rem; }
.hidden { display: none !important; }

/* Estructura */
.topbar {
  position: sticky; top: 0; z-index: 20;
  background: var(--card);
  border-bottom: 1px solid var(--line);
}
.topbar .in { max-width: 1180px; margin: 0 auto; padding: 10px 16px; display: flex; align-items: center; gap: 12px; min-height: 58px; }
.marca { display: flex; align-items: center; gap: 10px; font-weight: 700; text-decoration: none; color: var(--text); min-width: 0; }
.marca .logo { width: 32px; height: 32px; border-radius: 8px; background: var(--accent); color: var(--accent-ink); display: grid; place-items: center; flex: none; }
.marca span { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.spacer { flex: 1; }
.wrap { max-width: 1180px; margin: 0 auto; padding: 20px 16px 96px; }
.wrap.angosto { max-width: 780px; }
.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: clamp(16px, 3vw, 24px);
  margin: 0 0 16px;
  box-shadow: var(--shadow);
}
.card.cabecera { border-top: 6px solid var(--accent); }
.grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 16px; }
.fila { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; }

/* Formularios */
label { display: block; font-weight: 600; font-size: .9rem; margin: 12px 0 5px; }
input[type=text], input[type=password], input[type=number], input[type=datetime-local], textarea, select {
  width: 100%;
  font: inherit;
  font-size: 16px;
  color: var(--text);
  background: var(--card);
  border: 1px solid var(--line-strong);
  border-radius: 8px;
  padding: 10px 12px;
  min-height: 44px;
}
textarea { min-height: 120px; resize: vertical; line-height: 1.5; }
input:focus-visible, textarea:focus-visible, select:focus-visible, button:focus-visible, a:focus-visible {
  outline: 2px solid var(--accent); outline-offset: 2px;
}
.campo-linea {
  border: 0 !important; border-bottom: 1px solid var(--line-strong) !important; border-radius: 0 !important;
  background: transparent !important; padding-left: 0 !important; padding-right: 0 !important;
}
.campo-linea:focus-visible { outline: 0; border-bottom: 2px solid var(--accent) !important; }
.titulo-input { font-size: clamp(1.3rem, 1rem + 1.2vw, 1.8rem) !important; font-weight: 700; }
.check { display: flex; gap: 10px; align-items: flex-start; font-weight: 400; margin: 10px 0; cursor: pointer; }
.check input { width: 20px; height: 20px; margin-top: 2px; accent-color: var(--accent); flex: none; }

button, .btn {
  font: inherit; font-weight: 600; font-size: .95rem;
  border: 1px solid transparent; border-radius: 8px;
  padding: 10px 16px; min-height: 44px;
  cursor: pointer; touch-action: manipulation;
  background: var(--accent); color: var(--accent-ink);
  text-decoration: none; display: inline-flex; align-items: center; justify-content: center; gap: 6px;
  transition: background .15s, border-color .15s;
}
@media (hover: hover) { button:hover, .btn:hover { background: var(--accent-hover); } }
button.sec, .btn.sec { background: var(--card); color: var(--text); border-color: var(--line-strong); }
@media (hover: hover) { button.sec:hover, .btn.sec:hover { background: var(--accent-soft); } }
button.fantasma { background: transparent; color: var(--muted); padding: 8px 10px; min-height: 40px; }
@media (hover: hover) { button.fantasma:hover { background: var(--accent-soft); color: var(--text); } }
button.danger { background: var(--danger-soft); color: var(--danger); }
@media (hover: hover) { button.danger:hover { background: var(--danger-soft); border-color: var(--danger); } }
button:disabled { opacity: .5; cursor: not-allowed; }
.full { width: 100%; }

.alert { border-radius: 8px; padding: 10px 12px; margin: 10px 0; font-size: .95rem; }
.alert.err { background: var(--danger-soft); color: var(--danger); }
.alert.warn { background: var(--warn-soft); color: var(--warn); }
.alert.ok { background: var(--ok-soft); color: var(--ok); }
.alert.info { background: var(--accent-soft); color: var(--text); }

.chip { display: inline-block; font-size: .75rem; font-weight: 600; border-radius: 999px; padding: 2px 10px; white-space: nowrap; }
.chip.ok { background: var(--ok-soft); color: var(--ok); }
.chip.warn { background: var(--warn-soft); color: var(--warn); }
.chip.err { background: var(--danger-soft); color: var(--danger); }
.chip.neu { background: var(--accent-soft); color: var(--text); }

/* Examen (alumno) */
.barra-tiempo { position: sticky; top: 0; z-index: 15; background: var(--card); border-bottom: 1px solid var(--line); }
.barra-tiempo .in { max-width: 780px; margin: 0 auto; padding: 8px 16px; display: flex; align-items: center; gap: 14px; }
.reloj { font-variant-numeric: tabular-nums; font-weight: 700; font-size: 1.4rem; line-height: 1.1; }
.reloj.poco { color: var(--warn); }
.reloj.critico { color: var(--danger); }
.estado { margin-left: auto; font-size: .85rem; color: var(--muted); text-align: right; }
.progreso { height: 3px; background: var(--accent-soft); }
.progreso > div { height: 100%; background: var(--accent); width: 0; transition: width .3s; }
.q-num { font-size: .78rem; font-weight: 700; color: var(--muted); text-transform: uppercase; letter-spacing: .06em; }
.q-pts { float: right; font-size: .8rem; color: var(--muted); margin-left: 8px; }
.q-texto { white-space: pre-line; font-weight: 500; font-size: 1.02rem; margin: 6px 0 14px; }
.q-ayuda { white-space: pre-line; color: var(--muted); font-size: .92rem; margin: -6px 0 14px; }
.opc {
  display: flex; gap: 12px; align-items: flex-start;
  border: 1px solid var(--line); border-radius: 10px;
  padding: 12px 14px; margin: 8px 0; cursor: pointer; font-weight: 400; font-size: 1rem;
  transition: border-color .15s, background .15s;
}
@media (hover: hover) { .opc:hover { border-color: var(--line-strong); } }
.opc:has(input:checked) { border-color: var(--accent); background: var(--accent-soft); }
.opc input { margin-top: 3px; accent-color: var(--accent); width: 20px; height: 20px; flex: none; }
.fila-rel { border-top: 1px solid var(--line); padding-top: 14px; margin-top: 14px; }
.fila-rel:first-of-type { border-top: 0; margin-top: 0; padding-top: 0; }
.aviso-mini { color: var(--warn); font-size: .85rem; }
.seccion-card { background: var(--accent); color: var(--accent-ink); border: 0; }
.seccion-card .q-ayuda { color: inherit; opacity: .9; margin: 0; }
fieldset { border: 0; padding: 0; margin: 0; min-width: 0; }
fieldset:disabled .opc { cursor: default; }
@media (min-width: 900px) {
  /* En PC: opciones de relacionar en dos columnas */
  .rel-ops { display: grid; grid-template-columns: 1fr 1fr; gap: 0 10px; }
}

/* Panel */
.tabs { display: flex; gap: 4px; justify-content: center; border-bottom: 1px solid var(--line); background: var(--card); overflow-x: auto; }
.tabs a {
  padding: 12px 16px; text-decoration: none; color: var(--muted); font-weight: 600; font-size: .95rem;
  border-bottom: 3px solid transparent; white-space: nowrap;
}
.tabs a.activo { color: var(--accent); border-bottom-color: var(--accent); }
table { width: 100%; border-collapse: collapse; font-size: .92rem; }
th, td { text-align: left; padding: 10px; border-bottom: 1px solid var(--line); vertical-align: top; }
th { font-size: .76rem; text-transform: uppercase; letter-spacing: .05em; color: var(--muted); white-space: nowrap; }
td.num, th.num { text-align: right; font-variant-numeric: tabular-nums; }
tr.click { cursor: pointer; }
@media (hover: hover) { tr.click:hover { background: var(--accent-soft); } }
.tabla-scroll { overflow-x: auto; -webkit-overflow-scrolling: touch; }
.stat { margin: 0; }
.stat b { display: block; font-size: 1.7rem; font-variant-numeric: tabular-nums; line-height: 1.2; }
.correcto { color: var(--ok); font-weight: 600; }
.incorrecto { color: var(--danger); }
.resp-abierta { white-space: pre-wrap; background: var(--bg); border-radius: 8px; padding: 10px 12px; margin: 6px 0; }

/* Lista de exámenes */
.ex-card { display: flex; flex-direction: column; gap: 8px; margin: 0; }
.ex-card h3 { font-size: 1.05rem; margin: 0; overflow-wrap: anywhere; }
.ex-card .acciones { margin-top: auto; padding-top: 8px; border-top: 1px solid var(--line); }

/* Editor de preguntas */
.q-editor { position: relative; border-left: 4px solid transparent; }
.q-editor:focus-within { border-left-color: var(--accent); }
.q-editor .cab { display: grid; grid-template-columns: 1fr 220px; gap: 12px; align-items: start; }
@media (max-width: 640px) { .q-editor .cab { grid-template-columns: 1fr; } }
.op-edit { display: flex; align-items: center; gap: 8px; margin: 6px 0; }
.op-edit input[type=text] { flex: 1; min-width: 0; }
.op-edit .marca-correcta { width: 22px; height: 22px; accent-color: var(--ok); flex: none; cursor: pointer; }
.op-edit.es-correcta input[type=text] { border-color: var(--ok); background: var(--ok-soft); }
.pie-q { display: flex; flex-wrap: wrap; align-items: center; gap: 6px; border-top: 1px solid var(--line); margin-top: 14px; padding-top: 10px; }
.pie-q .pts { display: flex; align-items: center; gap: 6px; margin-right: auto; }
.pie-q .pts input { width: 84px; }
.barra-agregar { position: sticky; bottom: 12px; display: flex; justify-content: center; gap: 8px; z-index: 5; }
.barra-agregar button { box-shadow: 0 4px 14px rgba(0,0,0,.18); }
.guardado { font-size: .85rem; color: var(--muted); white-space: nowrap; }
.dos-col { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
@media (max-width: 640px) { .dos-col { grid-template-columns: 1fr; } }
.oculto-movil { }
@media (max-width: 640px) { .oculto-movil { display: none !important; } }