:root {
    --color-brand: #76b900;
    --color-brand-dark: #5c9100;
    --color-brand-soft: rgba(118, 185, 0, 0.12);
    --color-text: #1f2937;
    --color-text-muted: #5b6472;
    --color-bg: #ffffff;
    --color-bg-soft: #f7f9fb;
    --color-border: #d9e1ea;
    --color-code-bg: #f3f5f7;
    --shadow-sm: 0 2px 8px rgba(15, 23, 42, 0.06);
    --shadow-md: 0 12px 24px rgba(15, 23, 42, 0.08);
    --radius-sm: 8px;
    --radius-md: 14px;
    --radius-lg: 20px;
    --font-main: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Noto Sans SC", "PingFang SC", sans-serif;
    --font-mono: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
}

body {
    color: var(--color-text);
    font-family: var(--font-main);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.book-body {
    background: var(--color-bg);
}

.markdown-section {
    max-width: 960px;
}

.markdown-section h1,
.markdown-section h2,
.markdown-section h3,
.markdown-section h4 {
    color: var(--color-text);
    font-weight: 700;
    line-height: 1.35;
}

.markdown-section h1 {
    border-bottom: none;
    font-size: 2.35em;
    margin-bottom: 0.45em;
}

.markdown-section h2 {
    border-bottom: 1px solid var(--color-border);
    font-size: 1.65em;
    margin-top: 2.2em;
    padding-bottom: 0.25em;
}

.markdown-section h3 {
    color: var(--color-brand-dark);
    font-size: 1.25em;
}

.markdown-section p,
.markdown-section li {
    color: var(--color-text);
}

.markdown-section a {
    color: var(--color-brand-dark);
    text-decoration: none;
}

.markdown-section a:hover {
    text-decoration: underline;
}

.markdown-section pre {
    background: #111827;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
    padding: 1em 1.15em;
}

.markdown-section code {
    background: var(--color-code-bg);
    border-radius: 6px;
    color: #d63384;
    font-family: var(--font-mono);
    padding: 0.15em 0.35em;
}

.markdown-section pre code {
    background: transparent;
    color: inherit;
    padding: 0;
}

.markdown-section table {
    border: 1px solid var(--color-border);
    border-collapse: separate;
    border-radius: var(--radius-md);
    border-spacing: 0;
    box-shadow: var(--shadow-sm);
    overflow: hidden;
}

.markdown-section table th,
.markdown-section table td {
    border-bottom: 1px solid var(--color-border);
    padding: 0.85em 1em;
}

.markdown-section table th {
    background: var(--color-bg-soft);
    font-weight: 700;
}

.markdown-section table tr:last-child td {
    border-bottom: none;
}

.markdown-section blockquote {
    background: var(--color-bg-soft);
    border-left: 4px solid var(--color-brand);
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
    color: var(--color-text-muted);
    margin: 1.2em 0;
    padding: 1em 1.2em;
}

.book-summary {
    background: #fbfcfe;
    border-right: 1px solid var(--color-border);
}

.book-summary ul.summary li a {
    border-radius: 8px;
    color: var(--color-text);
    transition: background 0.2s ease;
}

.book-summary ul.summary li a:hover,
.book-summary ul.summary li.active > a {
    background: var(--color-brand-soft);
    color: var(--color-brand-dark);
}

.book-summary .book-search {
    border-bottom: 1px solid var(--color-border);
}

.book-summary .book-search input {
    border: 1px solid var(--color-border);
    border-radius: 999px;
}

.showcase-hero {
    background: linear-gradient(135deg, #111827 0%, #1f2937 65%, #243b0d 100%);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    color: #ffffff;
    margin: 1.4em 0 1.8em;
    padding: 2em 2em 1.6em;
}

.showcase-hero p {
    color: rgba(255, 255, 255, 0.92);
    margin: 0;
}

.showcase-kicker {
    font-size: 1.08em;
    max-width: 52rem;
}

.showcase-cta {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    margin-top: 1.2rem;
}

.showcase-cta a {
    background: #ffffff;
    border-radius: 999px;
    color: #111827 !important;
    display: inline-flex;
    font-weight: 700;
    padding: 0.75rem 1.1rem;
    text-decoration: none !important;
}

.showcase-cta a:hover {
    background: #f3f4f6;
}

.showcase-metrics {
    display: grid;
    gap: 1rem;
    grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
    margin: 1.4em 0 2em;
}

.showcase-metrics div {
    background: var(--color-bg-soft);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
    display: flex;
    flex-direction: column;
    gap: 0.2rem;
    padding: 1rem 1.1rem;
}

.showcase-metrics strong {
    color: var(--color-brand-dark);
    font-size: 1.9rem;
    line-height: 1;
}

.showcase-metrics span {
    color: var(--color-text-muted);
    font-size: 0.95rem;
}

.not-found-page {
    align-items: center;
    background: linear-gradient(180deg, #f7f9fb 0%, #ffffff 100%);
    display: flex;
    justify-content: center;
    margin: 0;
    min-height: 100vh;
}

.not-found-card {
    background: #ffffff;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    max-width: 32rem;
    padding: 2rem;
    text-align: center;
}

.not-found-code {
    color: var(--color-brand-dark);
    font-size: 4rem;
    font-weight: 800;
    line-height: 1;
    margin: 0 0 0.4rem;
}

@media (max-width: 768px) {
    .markdown-section {
        padding: 0 1rem;
    }

    .showcase-hero {
        padding: 1.4rem;
    }

    .showcase-cta a {
        width: 100%;
    }
}