:root {
    --primary: #0052CC;
    --primary-hover: #003d99;
    --primary-light: rgba(0, 82, 204, 0.08);
    --title-dark-blue: #061178;
    --text-primary: #1d1d1f;
    --text-secondary: #5a5a5a;
    --text-muted: #6b7280;
    --bg-white: #ffffff;
    --bg-light-blue: #f0f5ff;
    --bg-gray: #f8fafc;
    --bg-warm: #fff8e7;
    --border: rgba(0, 0, 0, 0.08);
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.06);
    --shadow-md: 0 12px 28px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 18px 48px rgba(0, 0, 0, 0.12);
    --radius-sm: 10px;
    --radius-md: 16px;
    --radius-lg: 24px;
}

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

html {
    scroll-behavior: smooth;
}

body {
    margin: 0;
    font-family: 'PingFang SC', 'Microsoft YaHei', 'Inter', -apple-system, sans-serif;
    color: var(--text-primary);
    background:
        radial-gradient(circle at top left, rgba(59, 130, 246, 0.14), transparent 28%),
        radial-gradient(circle at top right, rgba(0, 82, 204, 0.08), transparent 32%),
        linear-gradient(180deg, #f7fbff 0%, #ffffff 35%, #ffffff 100%);
    line-height: 1.7;
}

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

img {
    max-width: 100%;
    display: block;
}

.site-header {
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: saturate(180%) blur(18px);
    background: rgba(255, 255, 255, 0.9);
    border-bottom: 1px solid var(--border);
}

.site-header-inner,
.page-shell,
.site-footer-inner {
    width: min(1180px, calc(100% - 32px));
    margin: 0 auto;
}

.site-header-inner {
    min-height: 72px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 20px;
}

.brand {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    color: var(--title-dark-blue);
    text-decoration: none;
    font-weight: 800;
    font-size: 20px;
}

.brand span {
    color: var(--primary);
}

.header-nav {
    display: flex;
    align-items: center;
    gap: 18px;
    flex-wrap: wrap;
}

.header-nav a {
    text-decoration: none;
    color: var(--text-secondary);
    font-size: 14px;
    font-weight: 600;
}

.header-nav a:hover {
    color: var(--primary);
}

.header-nav .nav-cta {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 10px 18px;
    border-radius: 999px;
    background: var(--primary);
    color: #fff;
}

.page-shell {
    padding: 40px 0 80px;
}

.hero {
    display: grid;
    grid-template-columns: minmax(0, 1.2fr) minmax(320px, 0.8fr);
    gap: 28px;
    align-items: stretch;
}

.hero-card,
.content-card,
.guide-card,
.mini-card,
.author-card,
.cta-card {
    background: rgba(255, 255, 255, 0.94);
    border: 1px solid var(--border);
    box-shadow: var(--shadow-sm);
    border-radius: var(--radius-lg);
}

.hero-card {
    padding: 34px;
    background:
        linear-gradient(135deg, rgba(0, 82, 204, 0.08), rgba(255, 255, 255, 0.96)),
        #fff;
}

.eyebrow {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 6px 12px;
    border-radius: 999px;
    background: var(--primary-light);
    color: var(--primary);
    font-size: 13px;
    font-weight: 700;
}

.hero h1 {
    margin: 18px 0 16px;
    font-size: clamp(34px, 4vw, 52px);
    line-height: 1.1;
    color: var(--title-dark-blue);
}

.hero-lead {
    font-size: 18px;
    color: var(--text-secondary);
    max-width: 720px;
}

.hero-summary {
    margin-top: 24px;
    padding: 20px 22px;
    border-radius: var(--radius-md);
    background: #ffffff;
    border: 1px solid rgba(0, 82, 204, 0.15);
}

.hero-summary h2,
.content-card h2,
.content-card h3,
.cta-card h2,
.author-card h2 {
    margin: 0 0 12px;
    color: var(--title-dark-blue);
    line-height: 1.3;
}

.hero-summary p:last-child,
.content-card p:last-child,
.author-card p:last-child,
.cta-card p:last-child {
    margin-bottom: 0;
}

.hero-side {
    padding: 28px;
    display: grid;
    gap: 16px;
}

.meta-list,
.step-list,
.check-list {
    display: grid;
    gap: 12px;
}

.meta-item,
.step-item,
.check-item {
    padding: 14px 16px;
    border-radius: var(--radius-md);
    background: #fff;
    border: 1px solid rgba(0, 82, 204, 0.1);
}

.meta-item strong,
.step-item strong,
.check-item strong {
    display: block;
    color: var(--title-dark-blue);
    margin-bottom: 4px;
}

.btn-row {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    margin-top: 24px;
}

.btn-primary,
.btn-secondary {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    min-height: 46px;
    padding: 0 22px;
    border-radius: 999px;
    font-size: 15px;
    font-weight: 700;
    text-decoration: none;
    transition: 0.25s ease;
}

.btn-primary {
    background: var(--primary);
    color: #fff;
}

.btn-primary:hover {
    background: var(--primary-hover);
    transform: translateY(-1px);
}

.btn-secondary {
    color: var(--primary);
    border: 1px solid rgba(0, 82, 204, 0.2);
    background: #fff;
}

.btn-secondary:hover {
    background: var(--bg-light-blue);
}

.page-grid {
    display: grid;
    grid-template-columns: minmax(0, 1fr) 320px;
    gap: 28px;
    margin-top: 28px;
}

.content-column {
    display: grid;
    gap: 20px;
}

.content-card {
    padding: 28px 30px;
}

.content-card p,
.content-card li {
    color: var(--text-secondary);
}

.content-card ul,
.content-card ol {
    padding-left: 22px;
    margin: 14px 0;
}

.toc-card {
    position: sticky;
    top: 96px;
    padding: 24px;
}

.toc-card h2 {
    font-size: 20px;
    margin-top: 0;
    margin-bottom: 14px;
    color: var(--title-dark-blue);
}

.toc-card ol {
    display: grid;
    gap: 10px;
    margin: 0;
    padding-left: 20px;
}

.toc-card a {
    text-decoration: none;
    color: var(--text-secondary);
}

.toc-card a:hover {
    color: var(--primary);
}

.table-wrap {
    overflow-x: auto;
    margin: 16px 0;
}

table {
    width: 100%;
    border-collapse: collapse;
    min-width: 560px;
}

th,
td {
    padding: 14px 16px;
    text-align: left;
    border-bottom: 1px solid rgba(0, 0, 0, 0.08);
    vertical-align: top;
}

th {
    color: var(--title-dark-blue);
    background: rgba(0, 82, 204, 0.05);
}

.note-box,
.warning-box {
    padding: 18px 20px;
    border-radius: var(--radius-md);
    margin-top: 18px;
}

.note-box {
    background: var(--bg-light-blue);
    border: 1px solid rgba(0, 82, 204, 0.12);
}

.warning-box {
    background: var(--bg-warm);
    border: 1px solid rgba(245, 158, 11, 0.25);
}

.mini-grid,
.guides-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 18px;
}

.mini-card,
.guide-card {
    padding: 22px;
}

.mini-card h3,
.guide-card h3 {
    margin: 0 0 10px;
    color: var(--title-dark-blue);
}

.mini-card p,
.guide-card p {
    margin: 0;
    color: var(--text-secondary);
}

.guide-card a {
    display: inline-flex;
    margin-top: 16px;
    text-decoration: none;
    font-weight: 700;
}

.author-card,
.cta-card {
    padding: 28px;
    margin-top: 24px;
}

.author-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-top: 14px;
}

.author-tag {
    padding: 8px 12px;
    border-radius: 999px;
    background: var(--primary-light);
    color: var(--primary);
    font-size: 13px;
    font-weight: 700;
}

.faq-list {
    display: grid;
    gap: 16px;
}

.faq-item {
    padding: 18px 20px;
    background: #fff;
    border: 1px solid rgba(0, 0, 0, 0.08);
    border-radius: var(--radius-md);
}

.faq-item h3 {
    margin: 0 0 8px;
}

.site-footer {
    border-top: 1px solid var(--border);
    background: rgba(255, 255, 255, 0.8);
}

.site-footer-inner {
    min-height: 80px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    color: var(--text-muted);
    font-size: 14px;
}

.site-footer a {
    text-decoration: none;
    font-weight: 600;
}

@media (max-width: 980px) {
    .hero,
    .page-grid {
        grid-template-columns: 1fr;
    }

    .hero-card,
    .hero-side,
    .content-card,
    .author-card,
    .cta-card,
    .toc-card {
        padding: 24px;
    }

    .toc-card {
        position: static;
    }

    .mini-grid,
    .guides-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 720px) {
    .site-header-inner,
    .page-shell,
    .site-footer-inner {
        width: min(100% - 24px, 1180px);
    }

    .header-nav {
        gap: 10px;
    }

    .header-nav a {
        font-size: 13px;
    }

    .hero h1 {
        font-size: 30px;
    }

    .hero-lead {
        font-size: 16px;
    }

    .site-footer-inner {
        flex-direction: column;
        justify-content: center;
        padding: 18px 0;
        text-align: center;
    }
}