:root {
    --primary: #0066cc;
    --primary-focus: #0071e3;
    --ink: #1d1d1f;
    --ink-muted-80: #333333;
    --ink-muted-48: #7a7a7a;
    --hairline: #e0e0e0;
    --canvas: #ffffff;
    --canvas-parchment: #f5f5f7;
    --surface-tile-1: #272729;
    --on-dark: #ffffff;
    --body-muted: #cccccc;
}

* { box-sizing: border-box; }

body {
    margin: 0;
    background: var(--canvas);
    color: var(--ink);
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    font-size: 17px;
    line-height: 1.47;
    letter-spacing: -0.01em;
}

a { color: var(--primary); text-decoration: none; }
a:hover { color: var(--primary-focus); }

h1, h2, h3, h4 { font-weight: 600; letter-spacing: -0.02em; color: var(--ink); }

.global-nav { background: #000; color: #fff; }
.global-nav-title { font-size: 12px; letter-spacing: -0.01em; color: #fff; }

.sub-nav {
    background: rgba(245,245,247,0.9);
    backdrop-filter: blur(16px);
    height: 52px;
    display: flex;
    align-items: center;
    position: sticky;
    top: 0;
    z-index: 90;
    border-bottom: 1px solid var(--hairline);
}
.sub-nav-brand { font-size: 21px; font-weight: 600; color: var(--ink); }
.sub-nav-links { display: flex; list-style: none; gap: 24px; margin: 0; padding: 0; }
.sub-nav-links a { color: var(--ink); font-size: 14px; }
.sub-nav-toggle { border: none; }

.tile { padding: 64px 0; text-align: center; }
.tile-light { background: var(--canvas); }
.tile-parchment { background: var(--canvas-parchment); }
.tile-dark { background: var(--surface-tile-1); color: var(--on-dark); }
.tile-dark h1, .tile-dark h2, .tile-dark h3 { color: #fff; }
.tile-dark p { color: var(--body-muted); }

.tile h1 { font-size: 40px; margin-bottom: 16px; }
.tile p.lead { font-size: 21px; font-weight: 400; max-width: 640px; margin: 0 auto 24px; color: var(--ink-muted-80); }
.tile-dark p.lead { color: var(--body-muted); }

.btn-pill {
    display: inline-block;
    background: var(--primary);
    color: #fff;
    border-radius: 9999px;
    padding: 11px 22px;
    font-size: 17px;
    font-weight: 400;
    margin: 0 6px;
}
.btn-pill:hover { color: #fff; background: var(--primary-focus); }
.btn-pill-ghost {
    display: inline-block;
    background: transparent;
    color: var(--primary);
    border: 1px solid var(--primary);
    border-radius: 9999px;
    padding: 10px 21px;
    font-size: 17px;
    margin: 0 6px;
}
.tile-dark .btn-pill-ghost { color: #2997ff; border-color: #2997ff; }

.img-frame {
    border-radius: 0;
    overflow: hidden;
    max-width: 900px;
    margin: 32px auto 0;
    box-shadow: 3px 5px 30px rgba(0,0,0,0.22);
}
.img-frame img { width: 100%; display: block; }

.card-grid { padding: 64px 0; }
.card-topic {
    display: block;
    background: var(--canvas);
    border: 1px solid var(--hairline);
    border-radius: 18px;
    padding: 24px;
    height: 100%;
    color: var(--ink);
    text-align: left;
}
.card-topic:hover { color: var(--ink); border-color: #c7c7cc; }
.card-topic h3 { font-size: 17px; font-weight: 600; margin-bottom: 8px; }
.card-topic p { font-size: 14px; color: var(--ink-muted-48); margin: 0; }

.section-title { font-size: 32px; margin-bottom: 24px; text-align: center; }

.breadcrumb-strip { background: var(--canvas-parchment); padding: 10px 0; border-bottom: 1px solid var(--hairline); }
.breadcrumb-strip .breadcrumb { font-size: 13px; }
.breadcrumb-strip a { color: var(--ink-muted-48); }
.breadcrumb-strip .active { color: var(--ink); }

.article-wrap { padding: 48px 0; }
.article-content h2 { font-size: 26px; margin-top: 36px; margin-bottom: 14px; }
.article-content p { color: var(--ink-muted-80); margin-bottom: 16px; }
.article-header h1 { font-size: 34px; margin-bottom: 10px; }
.article-meta { color: var(--ink-muted-48); font-size: 13px; margin-bottom: 28px; }

.toc-box {
    background: var(--canvas-parchment);
    border-radius: 18px;
    padding: 20px;
    position: sticky;
    top: 76px;
}
.toc-box h4 { font-size: 12px; text-transform: uppercase; letter-spacing: 0.06em; color: var(--ink-muted-48); margin-bottom: 12px; }
.toc-box ul { list-style: none; padding: 0; margin: 0; }
.toc-box li { margin-bottom: 8px; }
.toc-box a { font-size: 14px; color: var(--ink-muted-80); }
.toc-box a:hover { color: var(--primary); }

.related-tile { padding: 48px 0; background: var(--canvas-parchment); }
.related-heading { font-size: 24px; margin-bottom: 24px; }
.related-card { display: block; background: var(--canvas); border-radius: 18px; padding: 20px; height: 100%; color: var(--ink); border: 1px solid var(--hairline); }
.related-card h3 { font-size: 16px; margin-bottom: 8px; }
.related-card p { color: var(--ink-muted-48); font-size: 13px; margin: 0; }

.faq-item { background: var(--canvas-parchment); border-radius: 11px; padding: 16px 20px; margin-bottom: 12px; text-align: left; }
.faq-item summary { cursor: pointer; font-weight: 600; color: var(--ink); list-style: none; }
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::before { content: '+'; color: var(--primary); margin-right: 10px; font-weight: 700; }
.faq-item[open] summary::before { content: '−'; }
.faq-item p { color: var(--ink-muted-80); margin: 12px 0 0; font-size: 15px; }

.form-control {
    border-radius: 11px;
    border: 1px solid var(--hairline);
}
.form-control:focus { border-color: var(--primary); box-shadow: 0 0 0 3px rgba(0,102,204,0.15); }
.form-label { font-size: 14px; color: var(--ink-muted-80); }

.site-footer { background: var(--canvas-parchment); padding: 56px 0 24px; color: var(--ink-muted-80); font-size: 14px; text-align: left; }
.footer-heading { font-size: 14px; font-weight: 600; margin-bottom: 14px; color: var(--ink); }
.footer-fine { font-size: 13px; color: var(--ink-muted-48); }
.footer-links { list-style: none; padding: 0; }
.footer-links li { margin-bottom: 10px; }
.footer-links a { color: var(--ink-muted-80); font-size: 14px; }
.footer-links a:hover { color: var(--primary); }
.footer-divider { border-color: var(--hairline); margin: 32px 0 16px; }
.footer-fine-print { font-size: 12px; color: var(--ink-muted-48); max-width: 800px; }

.cookie-banner {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: rgba(245,245,247,0.95);
    backdrop-filter: blur(20px);
    border-top: 1px solid var(--hairline);
    padding: 20px;
    z-index: 999;
    display: none;
}
.cookie-banner.show { display: block; }
.cookie-banner p { color: var(--ink-muted-80); font-size: 14px; margin: 0 0 12px; }

.form-status {
    margin-top: 16px;
    padding: 12px 16px;
    border-radius: 11px;
    background: rgba(0,102,204,0.1);
    color: #0066cc;
    display: none;
}
.form-status.show { display: block; }

@media (max-width: 768px) {
    .tile h1 { font-size: 30px; }
    .toc-box { position: static; margin-bottom: 24px; }
}