/* gfback — minimal mobile-first, system fonts, dark via prefers-color-scheme */
:root {
  --fg: #1a1a1a;
  --bg: #ffffff;
  --muted: #666;
  --link: #0a58ca;
}
@media (prefers-color-scheme: dark) {
  :root {
    --fg: #e8e8e8;
    --bg: #141414;
    --muted: #999;
    --link: #7ab0ff;
  }
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  color: var(--fg);
  background: var(--bg);
  line-height: 1.6;
  font-size: 17px;
}
main { max-width: 42rem; margin: 0 auto; padding: 0 1rem 3rem; }
a { color: var(--link); }
.site-header {
  display: flex; justify-content: space-between; align-items: center;
  padding: 0.75rem 1rem; border-bottom: 1px solid color-mix(in srgb, var(--fg) 15%, transparent);
}
.brand { font-weight: 700; text-decoration: none; color: var(--fg); }
.lang-switch { text-transform: uppercase; font-size: 0.85rem; text-decoration: none; border: 1px solid var(--muted); border-radius: 6px; padding: 0.15rem 0.5rem; }
.page h1 { font-size: 1.5rem; line-height: 1.3; }
.page-nav { display: flex; justify-content: space-between; margin: 2rem 0; font-size: 1.4rem; }
#comments { margin-top: 3rem; border-top: 1px solid color-mix(in srgb, var(--fg) 15%, transparent); padding-top: 1rem; }
.comments-placeholder { color: var(--muted); font-style: italic; }
.site-footer { padding: 1rem; text-align: center; color: var(--muted); font-size: 0.85rem; border-top: 1px solid color-mix(in srgb, var(--fg) 15%, transparent); }
.site-footer a { margin: 0 0.75rem; display: inline-block; }

/* preview (level B) + paywall */
.preview{border-left:3px solid #4a7dbd;padding:8px 16px;margin:16px 0;background:#f4f8fd}
.preview-task{font-weight:600}
.preview-transition{color:#555;font-style:italic}
.paywall{border:1px solid #ddd;border-radius:10px;padding:16px 20px;margin:24px 0}
.paywall .cta{display:inline-block;margin-top:8px;padding:10px 18px;background:#4a7dbd;color:#fff;border-radius:8px;text-decoration:none}
.paywall-title{font-weight:700;margin:14px 0 6px}
.paywall-list{margin:0;padding-left:20px;list-style:disc}
.paywall-list li{margin:4px 0}

/* diagrams (#4464): figure + always-present text fallback */
.diagram{margin:1.5rem 0;padding:.75rem;border:1px solid color-mix(in srgb, var(--fg) 15%, transparent);border-radius:10px}
.diagram figcaption{font-weight:600;margin-bottom:.5rem}
.diagram img{max-width:100%;height:auto}
pre.diagram-src{overflow-x:auto;white-space:pre-wrap;word-break:break-word;font-size:.85rem;color:var(--muted)}
.diagram-text{margin-top:.5rem;font-size:.9rem;color:var(--muted)}
.diagram-text ol{margin:.5rem 0 0;padding-left:1.4rem}
.diagram-text summary{cursor:pointer}

/* premium (level C) unlocked view */
.premium{border-left:3px solid #3d8b5f;padding:8px 16px;margin:16px 0}

/* ad slots (#4465): neutral containers, hidden when empty */
.ad-slot{margin:1.5rem 0;min-height:0}
.ad-slot:not(:empty){min-height:90px;display:flex;align-items:center;justify-content:center}

/* checkout / dostup / seans landing (#4471, #4484) */
.buy-box{border:1px solid #4a7dbd;border-radius:10px;padding:16px 20px;margin:24px 0}
.buy-box .price{font-size:1.2rem;font-weight:600;margin:0 0 8px}
.buy-box .cta{display:inline-block;margin-top:4px;padding:10px 18px;background:#4a7dbd;color:#fff;border-radius:8px;text-decoration:none}
.sales-closed{font-weight:600}
.access-form{display:flex;flex-wrap:wrap;gap:8px;margin:16px 0}
.access-form input{padding:10px 12px;border:1px solid #ccc;border-radius:8px;min-width:260px}
.access-form button{padding:10px 18px;background:#4a7dbd;color:#fff;border:none;border-radius:8px;cursor:pointer}
.form-error{color:#a33}

/* cookie consent banner (#task2) */
.cookie-banner{position:fixed;left:0;right:0;bottom:0;z-index:50;display:none;flex-wrap:wrap;gap:10px;align-items:center;justify-content:center;padding:12px 16px;background:var(--bg,#1e1e1e);border-top:1px solid color-mix(in srgb,var(--fg,#eee) 25%,transparent);font-size:.9rem}
.cookie-msg{margin:0 8px}
.cookie-actions{display:flex;gap:8px;flex-wrap:wrap}
.cookie-btn{padding:8px 16px;background:#4a7dbd;color:#fff;border:none;border-radius:8px;cursor:pointer}
.cookie-btn-secondary{background:transparent;color:inherit;border:1px solid color-mix(in srgb,var(--fg,#eee) 35%,transparent)}
.hero-cta-row{margin:0.5rem 0 1.5rem}
.hero-cta-row .cta{display:inline-block;padding:10px 20px;background:#4a7dbd;color:#fff;border-radius:8px;text-decoration:none;font-weight:600}
.page-section h2{font-size:1.2rem;margin-top:2rem}
.section-related a{margin-right:0.5rem}
.stat-bar{font-size:.9rem;color:var(--muted);border:1px solid color-mix(in srgb,var(--fg) 15%,transparent);border-radius:8px;padding:8px 12px;margin:0.5rem 0 1.5rem;display:inline-block}
.friction-line{display:block;font-size:.8rem;color:var(--muted);margin-top:6px}
.buy-box .cta{display:inline-block;padding:12px 24px;background:#4a7dbd;color:#fff;border-radius:8px;text-decoration:none;font-weight:600}
.trust-line{font-size:.8rem;color:var(--muted)}
details{margin:0.5rem 0}details summary{cursor:pointer;font-weight:600}