/* ══════════ Base ══════════ */
:root{
  --bg:#0b1220;
  --bg-soft:#111c31;
  --card:#16233c;
  --card-2:#1c2c49;
  --line:#26375a;
  --txt:#e8eefb;
  --txt-dim:#9db0d0;
  --accent:#3b82f6;
  --accent-2:#60a5fa;
  --ok:#22c55e;
  --ok-soft:#0f3d24;
  --bad:#ef4444;
  --bad-soft:#4a1414;
  --warn:#f59e0b;
  --r:14px;
  --shadow:0 10px 30px rgba(0,0,0,.35);
}
@media (prefers-color-scheme: light){
  :root{
    --bg:#f4f7fc; --bg-soft:#ffffff; --card:#ffffff; --card-2:#f0f4fb;
    --line:#dbe3f0; --txt:#122036; --txt-dim:#5a6c88;
    --ok-soft:#e6f8ec; --bad-soft:#fdeaea;
    --shadow:0 8px 24px rgba(18,32,54,.08);
  }
}
*{box-sizing:border-box}
html,body{margin:0;padding:0}
body{
  background:var(--bg); color:var(--txt);
  font:16px/1.55 system-ui,-apple-system,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
  -webkit-font-smoothing:antialiased;
  padding-bottom:48px;
}
.hidden{display:none !important}
a{color:var(--accent-2)}

/* ══════════ Topbar ══════════ */
.topbar{
  position:sticky; top:0; z-index:40;
  display:flex; align-items:center; justify-content:space-between; gap:12px;
  padding:12px max(16px, env(safe-area-inset-left)) 12px 16px;
  background:color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter:blur(10px);
  border-bottom:1px solid var(--line);
}
.brand{display:flex; align-items:center; gap:10px; background:none; border:0; color:inherit; cursor:pointer; padding:0; font:inherit}
.brand-mark{
  width:32px;height:32px;border-radius:9px;display:grid;place-items:center;
  background:linear-gradient(140deg,var(--accent),#8b5cf6); color:#fff; font-weight:800;
}
.brand-text{font-weight:700; letter-spacing:.2px}
.topbar-right{display:flex; align-items:center; gap:10px}
.timer{
  font-variant-numeric:tabular-nums; font-weight:700;
  background:var(--card); border:1px solid var(--line); border-radius:999px;
  padding:6px 14px;
}
.timer.warn{color:var(--warn); border-color:var(--warn)}
.timer.danger{color:#fff; background:var(--bad); border-color:var(--bad); animation:pulse 1s infinite}
@keyframes pulse{50%{opacity:.65}}

/* ══════════ Layout ══════════ */
main{max-width:820px; margin:0 auto; padding:20px 16px}
.screen{animation:fade .25s ease}
@keyframes fade{from{opacity:0;transform:translateY(6px)}to{opacity:1;transform:none}}

.hero{text-align:center; padding:18px 0 26px}
.hero h1{font-size:clamp(22px,5vw,32px); margin:0 0 8px; line-height:1.2}
.hero .sub{color:var(--txt-dim); margin:0}

/* ══════════ Cards ══════════ */
.cards{display:grid; gap:12px}
.card{
  display:flex; gap:14px; align-items:center; text-align:left;
  background:var(--card); border:1px solid var(--line); border-radius:var(--r);
  padding:16px; cursor:pointer; color:inherit; font:inherit; width:100%;
  transition:transform .12s, border-color .12s, background .12s;
}
.card:hover{transform:translateY(-2px); border-color:var(--accent)}
.card:active{transform:none}
.card-primary{background:linear-gradient(135deg,#2563eb,#7c3aed); border-color:transparent; color:#fff}
.card-primary p{color:rgba(255,255,255,.85) !important}
.card-ico{font-size:26px; width:44px; height:44px; display:grid; place-items:center;
  background:rgba(255,255,255,.12); border-radius:12px; flex:0 0 auto}
.card-primary .card-ico{background:rgba(255,255,255,.18)}
.card-body h3{margin:0 0 2px; font-size:17px}
.card-body p{margin:0; font-size:14px; color:var(--txt-dim)}

.opts-row{display:flex; flex-wrap:wrap; gap:16px; margin:22px 2px 8px}
.switch{display:flex; align-items:center; gap:8px; font-size:14px; color:var(--txt-dim); cursor:pointer; user-select:none}
.switch input{width:0;height:0;opacity:0;position:absolute}
.switch input + span{width:38px;height:22px;border-radius:999px;background:var(--line);position:relative;transition:.18s;flex:0 0 auto}
.switch input + span::after{content:"";position:absolute;top:3px;left:3px;width:16px;height:16px;border-radius:50%;background:#fff;transition:.18s}
.switch input:checked + span{background:var(--accent)}
.switch input:checked + span::after{transform:translateX(16px)}
.note{color:var(--txt-dim); font-size:13px; margin-top:18px; text-align:center}

/* ══════════ Botones ══════════ */
.btn{
  border:1px solid var(--line); background:var(--card); color:var(--txt);
  border-radius:11px; padding:11px 18px; font:600 15px/1 inherit; cursor:pointer;
  transition:.12s; display:inline-flex; align-items:center; justify-content:center; gap:6px;
}
.btn:hover{border-color:var(--accent)}
.btn:disabled{opacity:.45; cursor:not-allowed}
.btn-primary{background:var(--accent); border-color:var(--accent); color:#fff}
.btn-primary:hover{background:var(--accent-2); border-color:var(--accent-2)}
.btn-success{background:var(--ok); border-color:var(--ok); color:#04240f}
.btn-ghost{background:transparent}
.btn-danger-ghost{background:transparent; color:var(--bad); border-color:transparent}
.btn-sm{padding:8px 13px; font-size:14px}
.btn-block{width:100%}

/* ══════════ Examen ══════════ */
.exam-head{margin-bottom:14px}
.progress{height:6px; background:var(--card); border-radius:999px; overflow:hidden}
.progress-fill{height:100%; width:0; background:linear-gradient(90deg,var(--accent),#8b5cf6); transition:width .25s}
.exam-meta{display:flex; justify-content:space-between; font-size:13px; color:var(--txt-dim); margin-top:8px}

.qcard{
  background:var(--card); border:1px solid var(--line); border-radius:var(--r);
  padding:20px; box-shadow:var(--shadow);
}
.qnum{font-size:12px; color:var(--txt-dim); letter-spacing:.6px; text-transform:uppercase; margin-bottom:6px}
.qtext{font-size:clamp(17px,3.6vw,20px); line-height:1.4; margin:0 0 6px; font-weight:650}
.qhint{font-size:13px; color:var(--warn); margin-bottom:12px; min-height:0}
.qimg{max-width:100%; border-radius:10px; background:#fff; display:block; margin:4px 0 16px; padding:6px}

.options{display:grid; gap:9px}
.opt{
  display:flex; gap:12px; align-items:flex-start; text-align:left;
  background:var(--card-2); border:1.5px solid var(--line); border-radius:11px;
  padding:13px 14px; cursor:pointer; color:inherit; font:inherit; width:100%;
  transition:.12s;
}
.opt:hover{border-color:var(--accent)}
.opt.sel{border-color:var(--accent); background:color-mix(in srgb,var(--accent) 16%, var(--card-2))}
.opt-k{
  flex:0 0 auto; width:26px; height:26px; border-radius:8px; display:grid; place-items:center;
  background:var(--line); font-weight:700; font-size:13px; text-transform:uppercase;
}
.opt.sel .opt-k{background:var(--accent); color:#fff}
.opt-t{flex:1}
.opt-imgonly .opt-t{display:none}
.options.grid-letters{display:flex; flex-wrap:wrap; gap:10px}
.options.grid-letters .opt{width:auto; min-width:74px; justify-content:center}

.exam-nav{display:flex; gap:10px; margin-top:16px}
.exam-nav .btn{flex:1}
.finish-row{display:flex; justify-content:space-between; align-items:center; margin-top:18px; gap:10px}

/* ══════════ Resultado ══════════ */
.result-hero{text-align:center; padding:10px 0 6px}
.score-ring{
  width:132px; height:132px; border-radius:50%; margin:0 auto 14px;
  display:grid; place-items:center; font-size:30px; font-weight:800;
  background:conic-gradient(var(--ok) var(--p,0%), var(--line) 0);
  position:relative;
}
.score-ring::before{content:""; position:absolute; inset:10px; border-radius:50%; background:var(--bg)}
.score-ring span{position:relative}
.score-ring.fail{background:conic-gradient(var(--bad) var(--p,0%), var(--line) 0)}
#resultTitle{margin:0 0 4px; font-size:24px}
#resultLine{color:var(--txt-dim); margin:0}
.result-actions{display:flex; flex-wrap:wrap; gap:10px; justify-content:center; margin:20px 0 8px}
.sec-title{margin:28px 0 12px; font-size:18px}
.filter-row{display:flex; gap:8px; margin-bottom:14px; flex-wrap:wrap}
.chip{
  background:var(--card); border:1px solid var(--line); color:var(--txt-dim);
  border-radius:999px; padding:7px 15px; font:600 13px inherit; cursor:pointer;
}
.chip-on{background:var(--accent); border-color:var(--accent); color:#fff}

.review-list{display:grid; gap:12px}
.rev{
  background:var(--card); border:1px solid var(--line); border-left:4px solid var(--line);
  border-radius:var(--r); padding:15px;
}
.rev.ok{border-left-color:var(--ok)}
.rev.bad{border-left-color:var(--bad)}
.rev-head{display:flex; justify-content:space-between; gap:10px; align-items:baseline; margin-bottom:6px}
.rev-n{font-size:12px; color:var(--txt-dim)}
.rev-badge{font-size:12px; font-weight:700; padding:3px 9px; border-radius:999px}
.rev-badge.ok{background:var(--ok-soft); color:var(--ok)}
.rev-badge.bad{background:var(--bad-soft); color:var(--bad)}
.rev-q{font-weight:600; margin:0 0 8px}
.rev img{max-width:100%; border-radius:8px; background:#fff; padding:5px; margin-bottom:10px}
.rev-opts{display:grid; gap:5px; font-size:14.5px}
.rev-opt{padding:8px 11px; border-radius:8px; background:var(--card-2); display:flex; gap:9px}
.rev-opt b{flex:0 0 auto; text-transform:uppercase}
.rev-opt.correct{background:var(--ok-soft); color:var(--ok); font-weight:600}
.rev-opt.chosen-bad{background:var(--bad-soft); color:var(--bad); text-decoration:line-through}
.rev-expl{margin:10px 0 0; font-size:14px; color:var(--txt-dim); border-top:1px dashed var(--line); padding-top:9px}

/* ══════════ Historial ══════════ */
.stats-grid{display:grid; grid-template-columns:repeat(auto-fit,minmax(130px,1fr)); gap:10px; margin-bottom:20px}
.stat{background:var(--card); border:1px solid var(--line); border-radius:var(--r); padding:14px; text-align:center}
.stat b{display:block; font-size:24px}
.stat span{font-size:12.5px; color:var(--txt-dim)}
.history-list{display:grid; gap:8px}
.hrow{
  display:flex; justify-content:space-between; align-items:center; gap:10px;
  background:var(--card); border:1px solid var(--line); border-radius:11px; padding:12px 14px;
}
.hrow .h-date{font-size:13.5px; color:var(--txt-dim)}
.hrow .h-score{font-weight:700}
.hrow .h-score.ok{color:var(--ok)} .hrow .h-score.bad{color:var(--bad)}
.empty{color:var(--txt-dim); text-align:center; padding:26px; border:1px dashed var(--line); border-radius:var(--r)}

/* ══════════ Modales ══════════ */
.modal{position:fixed; inset:0; z-index:60; background:rgba(3,7,18,.68); display:grid; place-items:center; padding:16px; backdrop-filter:blur(3px)}
.modal-box{
  background:var(--bg-soft); border:1px solid var(--line); border-radius:16px;
  padding:22px; width:100%; max-width:430px; box-shadow:var(--shadow); max-height:86vh; overflow:auto;
}
.modal-box h3{margin:0 0 6px}
.modal-sub{color:var(--txt-dim); font-size:14px; margin:0 0 14px}
.modal-actions{display:flex; gap:10px; justify-content:flex-end; margin-top:8px}
#authForm{display:grid; gap:10px; margin-bottom:12px}
#authForm input{
  background:var(--card); border:1px solid var(--line); color:var(--txt);
  border-radius:10px; padding:12px 13px; font:15px inherit;
}
.auth-error{color:var(--bad); font-size:13.5px; margin:0}
.qgrid{display:grid; grid-template-columns:repeat(7,1fr); gap:7px; margin-bottom:14px}
.qgrid button{
  aspect-ratio:1; border-radius:9px; border:1px solid var(--line); background:var(--card);
  color:var(--txt-dim); font:600 13px inherit; cursor:pointer;
}
.qgrid button.done{background:var(--accent); border-color:var(--accent); color:#fff}
.qgrid button.cur{outline:2px solid var(--warn); outline-offset:1px}
.legend{display:flex; gap:16px; font-size:12.5px; color:var(--txt-dim); margin-bottom:14px}
.dot{width:10px;height:10px;border-radius:50%;display:inline-block;margin-right:5px}
.dot-done{background:var(--accent)} .dot-todo{background:var(--line)}

/* ══════════ Lightbox ══════════ */
.qimg, .rev img{cursor:zoom-in}
.lightbox{
  position:fixed; inset:0; z-index:90; background:rgba(3,7,18,.9);
  display:grid; place-items:center; padding:12px; cursor:zoom-out;
}
.lightbox img{max-width:100%; max-height:92vh; border-radius:10px; background:#fff; padding:8px}

/* ══════════ Toast ══════════ */
.toast{
  position:fixed; left:50%; bottom:24px; transform:translateX(-50%);
  background:var(--card); border:1px solid var(--line); color:var(--txt);
  padding:12px 18px; border-radius:999px; box-shadow:var(--shadow); z-index:80; font-size:14px;
}

@media (max-width:520px){
  .exam-nav{flex-wrap:wrap}
  .qgrid{grid-template-columns:repeat(6,1fr)}
  .qcard{padding:16px}
}