/* ==========================================================================
   The Human Body / El Cuerpo Humano — shared styles
   Bright, friendly, responsive, WCAG-AA contrast.
   ========================================================================== */

:root{
  --bg:#f2f7fb;
  --surface:#ffffff;
  --ink:#16283a;
  --ink-soft:#42586b;
  --brand:#0b6bcb;
  --brand-dark:#084e96;
  --accent:#e5533c;
  --good:#0f8a4d;
  --good-bg:#e3f6ec;
  --bad:#c22f3a;
  --bad-bg:#fdeaec;
  --ring:#7fb6ec;
  --line:#d8e3ee;
  --shadow:0 6px 20px rgba(11,44,80,.10);
  --radius:16px;
  --maxw:960px;
}

*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0;
  font-family:"Segoe UI",system-ui,-apple-system,Roboto,"Helvetica Neue",Arial,sans-serif;
  font-size:17px;
  line-height:1.6;
  color:var(--ink);
  background:
    radial-gradient(1200px 500px at 100% -10%, #dcecff 0, transparent 60%),
    radial-gradient(900px 400px at -10% 0, #ffe8e2 0, transparent 55%),
    var(--bg);
  min-height:100vh;
}
a{color:var(--brand-dark)}

/* ---- Header ---- */
.site-header{
  position:sticky;top:0;z-index:20;
  background:rgba(255,255,255,.92);
  backdrop-filter:blur(6px);
  border-bottom:1px solid var(--line);
}
.header-inner{
  max-width:var(--maxw);margin:0 auto;padding:10px 18px;
  display:flex;align-items:center;gap:14px;justify-content:space-between;
}
.brand{display:flex;align-items:center;gap:10px;text-decoration:none;color:var(--ink);font-weight:800}
.brand .logo{font-size:26px}
.brand h1{font-size:19px;margin:0;line-height:1.15}
.header-actions{display:flex;align-items:center;gap:10px}

.lang-toggle{display:inline-flex;border:2px solid var(--brand);border-radius:999px;overflow:hidden}
.lang-toggle button{
  border:0;background:var(--surface);color:var(--brand-dark);
  font-weight:700;padding:6px 14px;cursor:pointer;font-size:15px;
}
.lang-toggle button[aria-pressed="true"]{background:var(--brand);color:#fff}
.lang-toggle button:focus-visible{outline:3px solid var(--ring);outline-offset:-3px}

.back-link{font-weight:700;text-decoration:none;color:var(--brand-dark);font-size:15px;white-space:nowrap}
.back-link:hover{text-decoration:underline}

/* ---- Layout ---- */
main{max-width:var(--maxw);margin:0 auto;padding:22px 18px 60px}
.intro{
  background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);
  padding:18px 20px;box-shadow:var(--shadow);margin-bottom:22px;
}
.subject-hero{display:flex;align-items:center;gap:14px;margin:6px 0 18px}
.subject-hero .big-icon{font-size:44px}
.subject-hero h2{margin:0;font-size:28px}

/* ---- Gateway cards ---- */
.card-grid{
  display:grid;gap:16px;
  grid-template-columns:repeat(auto-fill,minmax(250px,1fr));
}
.card{
  background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);
  box-shadow:var(--shadow);padding:16px;display:flex;flex-direction:column;gap:12px;
  transition:transform .12s ease, box-shadow .12s ease;
}
.card:hover{transform:translateY(-3px);box-shadow:0 12px 26px rgba(11,44,80,.16)}
.card-top{display:flex;align-items:center;gap:12px}
.card-icon{font-size:34px;line-height:1}
.card-title{font-weight:800;font-size:18px}
.card-sub{color:var(--ink-soft);font-size:14px;margin-top:-2px}
.card-actions{display:flex;gap:8px;flex-wrap:wrap;margin-top:auto}
.chip{
  flex:1 1 auto;text-align:center;text-decoration:none;
  border:1.5px solid var(--brand);color:var(--brand-dark);background:#eef6ff;
  border-radius:10px;padding:8px 6px;font-weight:700;font-size:14px;
}
.chip:hover{background:var(--brand);color:#fff}
.progress{display:flex;align-items:center;gap:8px;font-size:14px;color:var(--ink-soft)}
.progress .bar{flex:1;height:9px;border-radius:999px;background:#e7eef6;overflow:hidden}
.progress .bar > i{display:block;height:100%;background:linear-gradient(90deg,var(--brand),#4aa3ff);width:0}
.badge-done{color:var(--good);font-weight:800}

/* ---- Tabs ---- */
.tabs{display:flex;gap:8px;flex-wrap:wrap;margin-bottom:16px}
.tab{
  border:1.5px solid var(--line);background:var(--surface);color:var(--ink-soft);
  border-radius:999px;padding:9px 16px;font-weight:700;cursor:pointer;font-size:15px;
}
.tab[aria-selected="true"]{background:var(--brand);border-color:var(--brand);color:#fff}
.tab:focus-visible{outline:3px solid var(--ring);outline-offset:2px}
.panel{display:none}
.panel.active{display:block;animation:fade .25s ease}
@keyframes fade{from{opacity:0;transform:translateY(6px)}to{opacity:1;transform:none}}

.section-card{
  background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);
  padding:20px 22px;box-shadow:var(--shadow);
}
.reading p{margin:0 0 14px}
.reading h3{margin:2px 0 12px;font-size:20px}
.analogy{
  border-left:5px solid var(--accent);background:#fff4f1;
  padding:10px 14px;border-radius:0 10px 10px 0;margin:14px 0;
}

/* ---- Video ---- */
.video-wrap{max-width:720px}
.ratio{position:relative;padding-top:56.25%;border-radius:12px;overflow:hidden;background:#000;border:1px solid var(--line)}
.ratio iframe{position:absolute;inset:0;width:100%;height:100%;border:0}
.video-meta{margin-top:12px;color:var(--ink-soft);font-size:15px}
.video-meta strong{color:var(--ink)}
.video-links{margin-top:10px;display:flex;flex-direction:column;gap:6px;font-size:15px}

/* ---- Quiz ---- */
.quiz-head{display:flex;align-items:center;justify-content:space-between;gap:12px;flex-wrap:wrap;margin-bottom:6px}
.q{border:1px solid var(--line);border-radius:12px;padding:16px 18px;margin:14px 0;background:#fbfdff}
.q .qtext{font-weight:700;margin-bottom:10px}
.q .qtype{font-size:13px;color:var(--ink-soft);font-weight:700;text-transform:uppercase;letter-spacing:.03em}
.options{display:flex;flex-direction:column;gap:9px}
.option{
  text-align:left;border:1.5px solid var(--line);background:#fff;border-radius:10px;
  padding:11px 14px;font-size:16px;cursor:pointer;color:var(--ink);font-family:inherit;
}
.option:hover:not(:disabled){border-color:var(--brand);background:#f2f8ff}
.option:focus-visible{outline:3px solid var(--ring);outline-offset:2px}
.option.correct{border-color:var(--good);background:var(--good-bg);font-weight:700}
.option.wrong{border-color:var(--bad);background:var(--bad-bg)}
.option:disabled{cursor:default}
.tf-row{display:flex;gap:10px}
.tf-row .option{flex:1;text-align:center}
.feedback{margin-top:11px;padding:10px 12px;border-radius:10px;font-size:15px;display:none}
.feedback.show{display:block}
.feedback.ok{background:var(--good-bg);color:#0a5d34}
.feedback.no{background:var(--bad-bg);color:#8f1f28}

/* drag & drop */
.dnd-instr{font-size:14px;color:var(--ink-soft);margin-bottom:10px}
.dnd-area{display:grid;grid-template-columns:1fr 1fr;gap:18px}
@media(max-width:620px){.dnd-area{grid-template-columns:1fr}}
.dnd-bank{display:flex;flex-wrap:wrap;gap:8px;align-content:flex-start}
.token{
  border:1.5px solid var(--brand);background:#eef6ff;color:var(--brand-dark);
  border-radius:999px;padding:7px 13px;font-weight:700;cursor:grab;font-size:15px;user-select:none;
}
.token[aria-pressed="true"]{background:var(--brand);color:#fff}
.token.placed{opacity:.35;pointer-events:none}
.slots{display:flex;flex-direction:column;gap:10px}
.slot{
  display:flex;align-items:center;gap:10px;border:1.5px dashed var(--line);
  border-radius:10px;padding:10px 12px;background:#fff;min-height:48px;
}
.slot .label{flex:1;color:var(--ink-soft)}
.slot.over{border-color:var(--brand);background:#f2f8ff}
.slot .drop{min-width:120px;font-weight:700}
.slot.correct{border-style:solid;border-color:var(--good);background:var(--good-bg)}
.slot.wrong{border-style:solid;border-color:var(--bad);background:var(--bad-bg)}

.btn{
  border:0;border-radius:12px;padding:11px 20px;font-weight:800;font-size:16px;cursor:pointer;
  background:var(--brand);color:#fff;box-shadow:var(--shadow);font-family:inherit;
}
.btn:hover{background:var(--brand-dark)}
.btn.secondary{background:#eef6ff;color:var(--brand-dark);border:1.5px solid var(--brand)}
.btn:focus-visible{outline:3px solid var(--ring);outline-offset:2px}
.quiz-actions{margin-top:18px;display:flex;gap:10px;flex-wrap:wrap}

.result{text-align:center;padding:26px 20px;border-radius:14px;background:#fff;border:1px solid var(--line)}
.result .score{font-size:44px;font-weight:900;color:var(--brand-dark)}
.result .pct{font-size:20px;color:var(--ink-soft)}
.result .msg{font-size:19px;font-weight:700;margin:12px 0}
.result.tier-hi .score{color:var(--good)}
.result.tier-lo .score{color:var(--accent)}

.footer{max-width:var(--maxw);margin:30px auto 0;padding:16px 18px;color:var(--ink-soft);font-size:14px;text-align:center}

.visually-hidden{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap}