:root {
  --primary: #2563eb;
  --primary-ink: #1d4ed8;
  --on-primary: #ffffff;
  --secondary: #f59e0b;
  --on-secondary: #0f172a;
  --accent: #db2777;
  --bg: #eff6ff;
  --fg: #0f172a;
  --card: #ffffff;
  --muted: #f1f5fd;
  --muted-fg: #475569;
  --border: #dbe5fb;
  --ok: #15803d;
  --ok-bg: #dcfce7;
  --bad: #b91c1c;
  --bad-bg: #fee2e2;
  --radius: 20px;
  --shadow: 0 2px 0 rgba(15, 23, 42, .06), 0 10px 24px -12px rgba(37, 99, 235, .35);
  --font-head: ui-rounded, "SF Pro Rounded", "Nunito", "Segoe UI", system-ui, sans-serif;
  --font-body: ui-rounded, "Nunito", "Segoe UI", system-ui, -apple-system, sans-serif;
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font: 400 1.0625rem/1.65 var(--font-body);
}
img, svg { max-width: 100%; height: auto; }
a { color: var(--primary-ink); text-underline-offset: 3px; }
a:hover { color: var(--accent); }
:focus-visible { outline: 3px solid var(--secondary); outline-offset: 3px; border-radius: 8px; }
h1, h2, h3 { font-family: var(--font-head); line-height: 1.2; letter-spacing: -.01em; }
h1 { font-size: clamp(2rem, 5vw, 3.1rem); margin: 0 0 .5em; }
h2 { font-size: clamp(1.5rem, 3.2vw, 2rem); margin: 1.6em 0 .5em; }
h3 { font-size: 1.2rem; margin: 1.2em 0 .4em; }
p, ul, ol { margin: 0 0 1em; }
.skip { position: absolute; left: -9999px; }
.skip:focus { left: 16px; top: 16px; background: var(--card); padding: 8px 12px; z-index: 10; }

.wrap { width: min(1100px, 100% - 32px); margin-inline: auto; }
.narrow { width: min(760px, 100% - 32px); margin-inline: auto; }

/* Header */
.site-header { background: var(--card); border-bottom: 1px solid var(--border); position: sticky; top: 0; z-index: 5; }
.site-header .wrap { display: flex; align-items: center; justify-content: space-between; gap: 16px; min-height: 68px; }
.brand { display: inline-flex; align-items: center; gap: 10px; text-decoration: none; color: var(--fg); font: 800 1.35rem/1 var(--font-head); }
.brand svg { width: 40px; height: 40px; flex: none; }
.brand sup { font-size: .55em; color: var(--muted-fg); }
.nav { display: flex; gap: 4px; flex-wrap: wrap; }
.nav a { padding: 10px 12px; border-radius: 12px; text-decoration: none; color: var(--fg); font-weight: 600; min-height: 44px; display: inline-flex; align-items: center; }
.nav a:hover, .nav a[aria-current="page"] { background: var(--muted); color: var(--primary-ink); }
.menu-btn { display: none; }
@media (max-width: 820px) {
  .menu-btn { display: inline-flex; align-items: center; justify-content: center; min-width: 44px; min-height: 44px; border: 2px solid var(--border); background: var(--card); border-radius: 12px; cursor: pointer; }
  .nav { display: none; position: absolute; left: 0; right: 0; top: 68px; background: var(--card); padding: 8px 16px 16px; border-bottom: 1px solid var(--border); flex-direction: column; }
  .nav.open { display: flex; }
}

/* Buttons */
.btn { display: inline-flex; align-items: center; justify-content: center; gap: 8px; min-height: 48px; padding: 12px 22px; border-radius: 16px; border: 3px solid transparent; font: 700 1.05rem/1 var(--font-head); text-decoration: none; cursor: pointer; transition: transform .15s ease-out, box-shadow .15s ease-out, background-color .15s; }
.btn:active { transform: translateY(2px); }
.btn-primary { background: var(--primary); color: var(--on-primary); box-shadow: 0 4px 0 var(--primary-ink); }
.btn-primary:hover { background: var(--primary-ink); color: var(--on-primary); }
.btn-ghost { background: var(--card); color: var(--fg); border-color: var(--border); }
.btn-ghost:hover { border-color: var(--primary); color: var(--primary-ink); }
.btn-row { display: flex; flex-wrap: wrap; gap: 12px; }

/* Hero */
.hero { padding: 56px 0 40px; }
.hero .wrap { display: grid; grid-template-columns: 1.15fr .85fr; gap: 40px; align-items: center; }
.hero p.lead { font-size: 1.2rem; color: var(--muted-fg); max-width: 36ch; }
.badge { display: inline-flex; align-items: center; gap: 6px; background: #fef3c7; color: #78350f; font-weight: 700; font-size: .9rem; padding: 6px 12px; border-radius: 999px; margin-bottom: 14px; }
.hero-art { background: var(--card); border-radius: 28px; box-shadow: var(--shadow); padding: 20px; border: 3px solid var(--border); }
@media (max-width: 820px) { .hero .wrap { grid-template-columns: 1fr; } .hero { padding-top: 32px; } }

/* Cards */
.grid { display: grid; gap: 18px; grid-template-columns: repeat(auto-fit, minmax(230px, 1fr)); }
.card { background: var(--card); border: 2px solid var(--border); border-radius: var(--radius); padding: 22px; box-shadow: var(--shadow); }
.card h3 { margin-top: 0; }
.card .icon { width: 44px; height: 44px; border-radius: 14px; display: grid; place-items: center; background: var(--muted); color: var(--primary); margin-bottom: 10px; }
.card .icon svg { width: 24px; height: 24px; }
a.card { text-decoration: none; color: inherit; display: block; transition: transform .15s ease-out, border-color .15s; }
a.card:hover { transform: translateY(-2px); border-color: var(--primary); }

section.block { padding: 28px 0; }
.trademark-band { background: var(--fg); color: #e2e8f0; border-radius: 24px; padding: 26px 28px; display: grid; gap: 8px; }
.trademark-band strong { color: #fff; }
.trademark-band a { color: #fde68a; }

.notice { background: #fff7ed; border: 2px solid #fed7aa; border-radius: 16px; padding: 14px 18px; color: #7c2d12; }
.article { background: var(--card); border-radius: 24px; padding: clamp(20px, 4vw, 44px); border: 2px solid var(--border); margin: 28px auto 40px; }
.article li { margin-bottom: .4em; }
.steps { counter-reset: s; list-style: none; padding: 0; }
.steps li { counter-increment: s; position: relative; padding: 0 0 18px 56px; }
.steps li::before { content: counter(s); position: absolute; left: 0; top: 0; width: 40px; height: 40px; border-radius: 12px; background: var(--primary); color: #fff; font: 800 1.1rem/40px var(--font-head); text-align: center; }
table { width: 100%; border-collapse: collapse; margin: 0 0 1em; font-size: .98rem; }
th, td { text-align: left; padding: 10px 12px; border-bottom: 1px solid var(--border); vertical-align: top; }
th { background: var(--muted); }
.table-scroll { overflow-x: auto; }
details { border: 2px solid var(--border); border-radius: 14px; padding: 12px 16px; margin-bottom: 10px; background: var(--card); }
summary { cursor: pointer; font-weight: 700; min-height: 28px; }
.breadcrumb { font-size: .9rem; color: var(--muted-fg); margin: 20px 0 0; }

/* Footer */
.site-footer { background: var(--card); border-top: 1px solid var(--border); padding: 32px 0; margin-top: 40px; font-size: .95rem; color: var(--muted-fg); }
.site-footer .cols { display: grid; gap: 24px; grid-template-columns: 2fr 1fr 1fr; }
.site-footer ul { list-style: none; padding: 0; }
.site-footer li { margin-bottom: 6px; }
@media (max-width: 720px) { .site-footer .cols { grid-template-columns: 1fr; } }

/* Quiz */
.quiz { background: var(--card); border: 3px solid var(--border); border-radius: 28px; padding: clamp(16px, 3vw, 32px); box-shadow: var(--shadow); margin: 24px 0 40px; }
.quiz-top { display: flex; justify-content: space-between; align-items: center; gap: 12px; flex-wrap: wrap; margin-bottom: 12px; }
.progress { flex: 1; min-width: 160px; height: 12px; background: var(--muted); border-radius: 999px; overflow: hidden; }
.progress span { display: block; height: 100%; background: var(--secondary); border-radius: 999px; transition: width .3s ease-out; }
.q-title { font: 700 1.3rem/1.35 var(--font-head); margin: 8px 0 14px; }
.q-figure { background: var(--muted); border-radius: 20px; padding: 16px; display: flex; justify-content: center; margin-bottom: 16px; }
.q-figure svg { max-height: 240px; }
.options { display: grid; grid-template-columns: repeat(auto-fit, minmax(120px, 1fr)); gap: 12px; }
.opt { position: relative; min-height: 64px; background: var(--card); border: 3px solid var(--border); border-radius: 18px; padding: 10px; cursor: pointer; font: 700 1.15rem/1.2 var(--font-head); color: var(--fg); display: flex; flex-direction: column; align-items: center; gap: 6px; transition: border-color .15s, transform .15s ease-out, background-color .15s; }
.opt:hover:not(:disabled) { border-color: var(--primary); transform: translateY(-2px); }
.opt .letter { font-size: .85rem; color: var(--muted-fg); }
.opt svg { width: 88px; height: 88px; }
.opt.correct { border-color: var(--ok); background: var(--ok-bg); }
.opt.wrong { border-color: var(--bad); background: var(--bad-bg); }
.opt:disabled { cursor: default; }
.feedback { margin-top: 16px; padding: 14px 18px; border-radius: 16px; font-weight: 600; }
.feedback.ok { background: var(--ok-bg); color: #14532d; }
.feedback.bad { background: var(--bad-bg); color: #7f1d1d; }
.level-pick { display: grid; gap: 12px; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); margin: 12px 0 18px; }
.level-pick label { display: flex; gap: 10px; align-items: center; padding: 14px 16px; border: 3px solid var(--border); border-radius: 16px; cursor: pointer; font-weight: 700; min-height: 56px; }
.level-pick input { width: 22px; height: 22px; accent-color: var(--primary); }
.level-pick label:has(input:checked) { border-color: var(--primary); background: var(--muted); }
.score-big { font: 800 3rem/1 var(--font-head); color: var(--primary); }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { transition: none !important; animation: none !important; scroll-behavior: auto !important; }
}