:root {
  --bg: #f3f5fb; --card: #ffffff; --txt: #161b2e; --muted: #6b7390; --line: #e3e7f1;
  --acc: #5b5bf0; --acc2: #a855f7; --acc-soft: #eceafe; --acc-txt: #fff;
  --ok: #0f9d6b; --ok-bg: #e3f7ef; --mal: #e0452b; --mal-bg: #fdebe7; --code: #eef0f7;
  --shadow: 0 1px 2px rgba(20,25,50,.04), 0 6px 20px rgba(20,25,50,.06);
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0d1017; --card: #161a24; --txt: #e8eaf2; --muted: #8d95ad; --line: #262c3b;
    --acc: #8b8cff; --acc2: #c084fc; --acc-soft: #23244a; --acc-txt: #0d1017;
    --ok: #3ddc97; --ok-bg: #10302a; --mal: #ff7a63; --mal-bg: #3a1a15; --code: #222838;
    --shadow: 0 1px 2px rgba(0,0,0,.3), 0 8px 24px rgba(0,0,0,.25);
  }
}
* { box-sizing: border-box; }
body { margin: 0; background: var(--bg); color: var(--txt); font: 16px/1.55 "Segoe UI Variable", "Segoe UI", system-ui, -apple-system, Roboto, sans-serif; -webkit-font-smoothing: antialiased; }

/* Cabecera */
.top { background: linear-gradient(120deg, var(--acc), var(--acc2)); color: #fff; padding: 26px 16px 56px; }
.top-in { max-width: 860px; margin: 0 auto; display: flex; align-items: center; gap: 14px; }
.logo { width: 48px; height: 48px; border-radius: 14px; display: grid; place-items: center; font-weight: 800; background: rgba(255,255,255,.18); backdrop-filter: blur(6px); flex-shrink: 0; }
.top h1 { margin: 0; font-size: 1.45rem; letter-spacing: -.01em; }
.top p { margin: 2px 0 0; opacity: .85; font-size: .9rem; }
main { max-width: 860px; margin: -36px auto 0; padding: 0 16px 110px; }

.card { background: var(--card); border: 1px solid var(--line); border-radius: 18px; padding: 22px; margin-bottom: 16px; box-shadow: var(--shadow); }
h2 { font-size: .8rem; text-transform: uppercase; letter-spacing: .08em; color: var(--muted); margin: 4px 0 12px; }

/* Botones */
button { font: inherit; cursor: pointer; border-radius: 12px; padding: 10px 18px; border: 1px solid transparent; transition: transform .12s, box-shadow .2s, background .2s, border-color .2s; }
button:active { transform: scale(.97); }
button:disabled { opacity: .45; cursor: not-allowed; }
.primary { background: linear-gradient(120deg, var(--acc), var(--acc2)); color: #fff; font-weight: 600; box-shadow: 0 6px 18px -6px var(--acc); }
.primary:hover:not(:disabled) { box-shadow: 0 10px 24px -8px var(--acc); }
.ghost { background: var(--card); color: var(--txt); border-color: var(--line); }
.ghost:hover { border-color: var(--acc); color: var(--acc); }
.link { background: var(--acc-soft); color: var(--acc); padding: 5px 12px; font-size: .85rem; border-radius: 999px; font-weight: 600; }
.row-btns { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 12px; }
#empezar { width: 100%; padding: 14px; font-size: 1.05rem; }

/* Temas como chips */
.temas { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 8px; margin-bottom: 22px; }
.tema { display: flex; align-items: center; gap: 10px; padding: 11px 14px; border: 1.5px solid var(--line); border-radius: 12px; cursor: pointer; transition: border-color .2s, background .2s; user-select: none; }
.tema:hover { border-color: var(--acc); }
.tema input { accent-color: var(--acc); width: 16px; height: 16px; }
.tema:has(input:checked) { border-color: var(--acc); background: var(--acc-soft); }
.tema span { flex: 1; font-size: .93rem; }
.tema em { font-style: normal; color: var(--acc); background: var(--card); border-radius: 999px; padding: 1px 9px; font-size: .78rem; font-weight: 600; }

.opts { display: flex; flex-wrap: wrap; gap: 12px 24px; align-items: center; margin-bottom: 20px; }
.opts select { font: inherit; margin-left: 8px; padding: 6px 10px; border-radius: 10px; border: 1.5px solid var(--line); background: var(--card); color: var(--txt); }
.chk { display: flex; align-items: center; gap: 8px; cursor: pointer; }
.chk input { accent-color: var(--acc); width: 16px; height: 16px; }
.hint { color: var(--muted); font-size: .88rem; margin: 12px 0 0; text-align: center; }

/* Preguntas */
.preguntas { list-style: none; padding: 0; margin: 0; counter-reset: n; }
.preg { counter-increment: n; background: var(--card); border: 1px solid var(--line); border-radius: 18px; padding: 20px; margin-bottom: 14px; box-shadow: var(--shadow); position: relative; overflow: hidden; animation: entra .35s ease both; }
.preg::before { content: ""; position: absolute; inset: 0 auto 0 0; width: 5px; background: var(--line); }
.preg.bien::before { background: var(--ok); }
.preg.fallo::before { background: var(--mal); }
.preg.blanco::before { background: var(--muted); }
@keyframes entra { from { opacity: 0; transform: translateY(8px); } }
.tag { display: inline-block; font-size: .72rem; font-weight: 600; color: var(--acc); background: var(--acc-soft); padding: 3px 10px; border-radius: 999px; letter-spacing: .02em; }
.enun { margin: 10px 0 14px; font-weight: 600; font-size: 1.04rem; }
.enun::before { content: counter(n) ". "; color: var(--acc); }
.opciones { display: grid; gap: 8px; counter-reset: l; }
.op { counter-increment: l; display: flex; gap: 12px; align-items: center; padding: 11px 14px; border: 1.5px solid var(--line); border-radius: 12px; cursor: pointer; transition: border-color .15s, background .15s; }
.op input { position: absolute; opacity: 0; pointer-events: none; }
.op::before { content: counter(l, upper-alpha); flex-shrink: 0; width: 28px; height: 28px; border-radius: 8px; display: grid; place-items: center; font-weight: 700; font-size: .85rem; background: var(--code); color: var(--muted); transition: background .15s, color .15s; }
.op:hover { border-color: var(--acc); }
.op:has(input:checked) { border-color: var(--acc); background: var(--acc-soft); }
.op:has(input:checked)::before { background: var(--acc); color: #fff; }
.op:has(input:focus-visible) { outline: 2px solid var(--acc); outline-offset: 2px; }
.opciones .op.ok { background: var(--ok-bg); border-color: var(--ok); }
.opciones .op.ok::before { content: "✓"; background: var(--ok); color: #fff; }
.opciones .op.mal { background: var(--mal-bg); border-color: var(--mal); }
.opciones .op.mal::before { content: "✕"; background: var(--mal); color: #fff; }
.op:has(input:disabled) { cursor: default; }
.expl { margin: 14px 0 0; padding: 12px 14px; border-radius: 12px; background: var(--code); font-size: .92rem; border-left: 3px solid var(--acc); }
.expl::before { content: "💡 "; }
code { font-family: "Cascadia Code", Consolas, monospace; background: var(--code); padding: 1px 6px; border-radius: 6px; font-size: .86em; word-break: break-word; }
.expl code, .op code { background: var(--card); }

/* Barra inferior */
.barra { position: fixed; left: 50%; bottom: 14px; transform: translateX(-50%); width: min(828px, calc(100% - 32px)); display: flex; justify-content: space-between; align-items: center; gap: 10px;
  padding: 10px 10px 10px 18px; background: color-mix(in srgb, var(--card) 82%, transparent); backdrop-filter: blur(12px); border: 1px solid var(--line); border-radius: 16px; box-shadow: var(--shadow); }
.barra div { display: flex; gap: 8px; }
#contador { font-weight: 600; color: var(--muted); font-size: .92rem; }

/* Resultado */
.resultado { text-align: center; }
.nota { --c: var(--ok); width: 140px; height: 140px; margin: 4px auto 14px; border-radius: 50%; display: grid; place-items: center;
  background: conic-gradient(var(--c) calc(var(--p) * 1%), var(--line) 0); animation: entra .5s ease both; }
.nota.suspenso { --c: var(--mal); }
.nota span { width: 112px; height: 112px; border-radius: 50%; background: var(--card); display: grid; place-items: center; font-size: 2rem; font-weight: 800; color: var(--c); line-height: 1; }
.nota small { display: block; font-size: .85rem; color: var(--muted); font-weight: 600; }
.stats { display: flex; flex-wrap: wrap; justify-content: center; gap: 8px; margin: 0 0 18px; }
.stats span { padding: 4px 12px; border-radius: 999px; font-size: .88rem; font-weight: 600; background: var(--code); }
.s-ok { color: var(--ok); } .s-mal { color: var(--mal); } .s-bl { color: var(--muted); }
.resultado .row-btns { justify-content: center; margin: 0; }