/* Base */
:root{
  --bg:#ffffff; --fg:#0f172a; --muted:#6b7280; --line:#e5e7eb; --brand:#2563eb;
  --brand-ink:#1e40af; --card:#ffffff; --shadow:0 1px 2px rgba(0,0,0,.06),0 4px 12px rgba(0,0,0,.04);
}
*{box-sizing:border-box}
html,body{height:100%}
body{margin:0;font-family:ui-sans-serif,system-ui,-apple-system,Segoe UI,Roboto,Ubuntu,Arial,sans-serif;color:var(--fg);background:var(--bg);-webkit-font-smoothing:antialiased}
img{max-width:100%;display:block;border-radius:12px}
a{color:var(--brand);text-decoration:none}
a:hover{text-decoration:underline}

/* Layout */
.container{max-width:1024px;margin:0 auto;padding:16px}
.site-header{position:sticky;top:0;background:#fff;border-bottom:1px solid var(--line);z-index:20}
.header-inner{display:flex;align-items:center;justify-content:space-between}
.brand{font-weight:800;letter-spacing:.2px;color:var(--fg)}
.nav a{margin-left:16px;color:var(--fg);opacity:.8}
.nav a:hover{opacity:1}
.site-footer{border-top:1px solid var(--line);background:#fafafa}

/* Typography */
.title{font-size:clamp(28px,4vw,36px);line-height:1.2;margin:10px 0 6px;font-weight:800}
.lead{color:var(--muted);margin:0 0 18px}
.hint{color:var(--muted);font-size:13px;margin-top:8px}
.alert{background:#fff3f3;border:1px solid #ffd1d1;padding:12px 14px;border-radius:12px}

/* Cards & grid */
.card{background:var(--card);border:1px solid var(--line);border-radius:16px;box-shadow:var(--shadow);padding:16px}
.grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:16px}

/* Form */
.form label{display:block;font-weight:600;margin-bottom:8px}
.form .row{display:flex;gap:8px;align-items:center;flex-wrap:wrap}
.form input, .form select{padding:12px 14px;border:1px solid var(--line);border-radius:12px;font-size:16px}
.form input[type=text], .form input[type=number]{width:100%}
.form button{padding:12px 18px;border:0;border-radius:12px;background:var(--brand);color:#fff;font-weight:700;cursor:pointer}
.form button:hover{background:var(--brand-ink)}

/* Buttons */
.btn{display:inline-block;padding:10px 14px;border:1px solid var(--line);border-radius:12px;background:#fff;color:var(--fg);font-weight:600}
.btn:hover{box-shadow:var(--shadow)}
.btn.primary{background:var(--brand);border-color:var(--brand);color:#fff}
.btn.primary:hover{background:var(--brand-ink)}

/* Ads blocks */
.ad{margin:16px 0}

/* SEO section */
.seo{margin:32px 0;padding:24px;border-top:1px solid var(--line)}
.seo h2{font-size:22px;margin-bottom:12px}
.seo p{margin:0 0 12px;line-height:1.6;color:var(--muted)}

/* Question card */
.question .grid{grid-template-columns:repeat(auto-fit,minmax(200px,1fr))}