:root {
    --bg-body: #f8fafc;
    --card-bg: #ffffff;
    --surface-muted: #eef2ff;
    --text-main: #0f172a;
    --text-secondary: #64748b;
    --accent-color: #4f46e5;
    --accent-strong: #3730a3;
    --border-color: #e2e8f0;
}

[data-theme="dark"] {
    --bg-body: #0f172a;
    --card-bg: #1e293b;
    --surface-muted: #1f2a44;
    --text-main: #f8fafc;
    --text-secondary: #94a3b8;
    --accent-color: #818cf8;
    --accent-strong: #c7d2fe;
    --border-color: #334155;
}

*,
*::before,
*::after {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: 'Roboto', -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
    background: var(--bg-body);
    color: var(--text-main);
    line-height: 1.7;
    transition: background-color 0.3s ease, color 0.3s ease;
}

a {
    color: var(--accent-color);
}

header {
    position: sticky;
    top: 0;
    z-index: 30;
    backdrop-filter: blur(10px);
    background: color-mix(in srgb, var(--bg-body) 86%, transparent);
    border-bottom: 1px solid var(--border-color);
}

.nav-shell,
.page-shell,
.footer-shell {
    max-width: 1100px;
    margin: 0 auto;
    padding-left: 1rem;
    padding-right: 1rem;
}

.nav-shell {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    min-height: 72px;
}

.brand {
    color: var(--text-main);
    text-decoration: none;
    font-weight: 700;
    letter-spacing: -0.02em;
}

.nav-links {
    display: flex;
    gap: 1rem;
    align-items: center;
}

.nav-links a {
    text-decoration: none;
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.nav-links a:hover,
.brand:hover {
    color: var(--accent-color);
}

.theme-toggle {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    color: var(--text-main);
    width: 44px;
    height: 44px;
    border-radius: 0.75rem;
    cursor: pointer;
    font-size: 1.1rem;
}

.hero {
    padding: 4.5rem 0 2.5rem;
}

.eyebrow {
    display: inline-block;
    font-size: 0.8rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--accent-color);
    margin-bottom: 0.85rem;
}

.hero h1 {
    font-size: clamp(2rem, 4vw, 3.3rem);
    line-height: 1.1;
    letter-spacing: -0.04em;
    margin: 0 0 1rem;
}

.hero p,
.lead,
.section-copy,
.article-body p,
.article-body li,
.card p,
.faq p {
    color: var(--text-secondary);
}

.hero-actions,
.card-grid,
.chip-row,
.footer-links {
    display: flex;
    flex-wrap: wrap;
    gap: 0.9rem;
}

.btn-primary,
.btn-secondary {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 44px;
    padding: 0.8rem 1.2rem;
    border-radius: 9999px;
    text-decoration: none;
    font-weight: 600;
}

.btn-primary {
    background: var(--accent-color);
    color: white;
}

.btn-secondary {
    border: 1px solid var(--border-color);
    color: var(--text-main);
    background: var(--card-bg);
}

.page-shell {
    padding-top: 1rem;
    padding-bottom: 3rem;
}

.card-grid {
    gap: 1.25rem;
}

.card {
    flex: 1 1 240px;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 1.25rem;
    padding: 1.4rem;
    text-decoration: none;
    color: inherit;
}

.card h2,
.card h3,
.section-block h2,
.article-body h2,
.article-body h3,
.faq h3 {
    margin-top: 0;
    letter-spacing: -0.02em;
}

.section-block,
.article-layout,
.faq,
.related-links {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 1.25rem;
    padding: 1.6rem;
    margin-top: 1.5rem;
}

.breadcrumbs {
    font-size: 0.92rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.breadcrumbs a {
    text-decoration: none;
}

.article-layout {
    padding: 2rem;
}

.article-meta {
    margin-bottom: 1rem;
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.article-body ul,
.article-body ol {
    padding-left: 1.25rem;
}

.callout {
    background: var(--surface-muted);
    border: 1px solid var(--border-color);
    border-radius: 1rem;
    padding: 1rem 1.1rem;
    margin: 1.2rem 0;
}

.chip-row {
    margin-top: 1rem;
}

.chip {
    background: var(--surface-muted);
    border: 1px solid var(--border-color);
    color: var(--text-main);
    border-radius: 9999px;
    padding: 0.5rem 0.8rem;
    font-size: 0.88rem;
}

footer {
    border-top: 1px solid var(--border-color);
    padding: 2rem 0 2.5rem;
}

.footer-shell {
    color: var(--text-secondary);
    font-size: 0.94rem;
}

.footer-links a {
    text-decoration: none;
}

@media (max-width: 780px) {
    .nav-shell {
        align-items: flex-start;
        flex-direction: column;
        padding-top: 0.8rem;
        padding-bottom: 0.8rem;
    }

    .nav-links {
        width: 100%;
        justify-content: space-between;
    }

    .article-layout {
        padding: 1.35rem;
    }
}