:root {
    --primary: #2563eb;
    --primary-dark: #1d4ed8;
    --secondary: #10b981;
    --accent: #8b5cf6;
    --dark: #0f172a;
    --text: #1e293b;
    --text-light: #475569;
    --muted: #94a3b8;
    --surface: #ffffff;
    --surface-alt: #f8fafc;
    --border: #e2e8f0;
    --shadow-md: 0 15px 35px rgba(15, 23, 42, 0.12);
    --shadow-sm: 0 4px 12px rgba(15, 23, 42, 0.08);
    --radius-sm: 12px;
    --radius-md: 18px;
    --radius-lg: 24px;
    --transition: all 0.3s ease;
    --container-max: 1080px;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Poppins', 'Noto Sans SC', sans-serif;
    background: linear-gradient(160deg, #f1f5f9 0%, #e0f2fe 100%);
    color: var(--text);
    line-height: 1.6;
    min-height: 100vh;
}

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

a {
    color: inherit;
    text-decoration: none;
    transition: color 0.2s ease;
}

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

.container {
    width: min(92%, var(--container-max));
    margin: 0 auto;
}

.site-shell {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    padding-bottom: 72px;
}

.site-header {
    background: var(--surface);
    position: sticky;
    top: 0;
    z-index: 100;
    border-bottom: 1px solid rgba(148, 163, 184, 0.2);
    box-shadow: var(--shadow-sm);
}

.site-header .header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 14px 0;
}

.brand {
    display: inline-flex;
    align-items: center;
    gap: 12px;
    font-weight: 700;
    font-size: 1.25rem;
    color: var(--primary);
}

.brand i {
    font-size: 1.5rem;
}

.primary-nav {
    display: flex;
    align-items: center;
    gap: 12px;
}

.primary-nav-list {
    display: flex;
    align-items: center;
    gap: 18px;
    list-style: none;
    font-size: 0.95rem;
}

.primary-nav a {
    padding: 8px 14px;
    border-radius: 999px;
    color: var(--text-light);
    border: 1px solid transparent;
}

.primary-nav a:hover,
.primary-nav a.active {
    color: var(--primary);
    border-color: rgba(37, 99, 235, 0.3);
    background: rgba(37, 99, 235, 0.08);
}

.nav-toggle {
    display: none;
    background: transparent;
    border: none;
    font-size: 1.4rem;
    color: var(--primary);
    cursor: pointer;
}

.site-main {
    flex: 1;
    padding: 32px 0 56px;
}

section + section {
    margin-top: 48px;
}

.hero {
    background: linear-gradient(135deg, var(--primary), var(--accent));
    color: white;
    border-radius: var(--radius-lg);
    padding: clamp(32px, 8vw, 48px);
    position: relative;
    overflow: hidden;
    box-shadow: var(--shadow-md);
}

.hero::after {
    content: '';
    position: absolute;
    inset: 0;
    background: radial-gradient(circle at 0% 0%, rgba(255,255,255,0.2), transparent 55%);
}

.hero-content {
    position: relative;
    z-index: 1;
    display: grid;
    gap: 18px;
}

.hero h1 {
    font-size: clamp(1.9rem, 4.8vw, 2.6rem);
    font-weight: 700;
    letter-spacing: -0.02em;
}

.hero p {
    font-size: 1.05rem;
    color: rgba(255, 255, 255, 0.88);
}

.hero-notice {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    margin-top: 6px;
    padding: 12px 16px;
    border-radius: 14px;
    background: rgba(15, 23, 42, 0.25);
    border: 1px solid rgba(255, 255, 255, 0.35);
    color: #fef9c3;
    font-weight: 600;
    box-shadow: 0 12px 26px rgba(15, 23, 42, 0.22);
}

.hero-notice i {
    color: #facc15;
    font-size: 1.1rem;
}

.cta-group {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    margin-top: 4px;
}

.button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    padding: 14px 20px;
    border-radius: 14px;
    font-weight: 600;
    border: none;
    cursor: pointer;
    transition: var(--transition);
    font-size: 1rem;
}

.button i {
    font-size: 1.1rem;
}

.button-primary {
    background: var(--surface);
    color: var(--primary);
    box-shadow: 0 12px 25px rgba(15, 23, 42, 0.16);
}

.button-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 16px 28px rgba(15, 23, 42, 0.22);
}

.button-secondary {
    background: rgba(255, 255, 255, 0.92);
    color: var(--primary);
    border: 1px solid rgba(255, 255, 255, 0.7);
    box-shadow: 0 10px 22px rgba(15, 23, 42, 0.14);
}

.button-secondary:hover {
    background: #ffffff;
    color: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: 0 14px 26px rgba(15, 23, 42, 0.18);
}

.section-headline {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    margin-bottom: 24px;
}

.section-headline h2 {
    font-size: clamp(1.4rem, 3.6vw, 1.8rem);
    font-weight: 600;
    color: var(--text);
    position: relative;
    padding-left: 16px;
}

.section-headline h2::before {
    content: '';
    width: 6px;
    height: 100%;
    border-radius: 999px;
    background: var(--primary);
    position: absolute;
    left: 0;
    top: 50%;
    transform: translateY(-50%);
}

.cards-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 20px;
}

.info-card {
    background: var(--surface);
    border-radius: var(--radius-md);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    display: flex;
    flex-direction: column;
    transition: var(--transition);
    min-height: 100%;
}

.info-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 18px 28px rgba(15, 23, 42, 0.12);
}

.info-card__header {
    display: flex;
    align-items: center;
    gap: 16px;
    padding: 20px 22px;
    background: linear-gradient(135deg, var(--primary), var(--accent));
    color: white;
}

.info-card__header i {
    font-size: 2rem;
}

.info-card__body {
    display: grid;
    gap: 16px;
    padding: 22px;
    color: var(--text-light);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
    gap: 18px;
}

.feature-tile {
    background: var(--surface);
    padding: 28px 20px;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
    text-align: center;
    display: grid;
    gap: 12px;
}

.feature-tile i {
    font-size: 2rem;
    color: var(--primary);
}

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

.faq-item {
    background: var(--surface);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
    overflow: hidden;
    border-left: 3px solid transparent;
}

.faq-question {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    padding: 18px 22px;
    cursor: pointer;
    font-weight: 600;
    color: var(--text);
}

.faq-question i {
    transition: transform 0.3s ease, color 0.3s ease;
    color: var(--muted);
    transform: rotate(0deg);
}

.faq-answer {
    padding: 0 22px;
    max-height: 0;
    overflow: hidden;
    transition: var(--transition);
    color: var(--text-light);
}

.faq-item.active .faq-answer {
    padding: 0 22px 20px;
    max-height: 440px;
}

.faq-answer {
    border-top: 1px solid rgba(148, 163, 184, 0.2);
}

.faq-item.active {
    border-left-color: var(--primary);
    box-shadow: 0 12px 24px rgba(37, 99, 235, 0.12);
}

.faq-item.active .faq-question {
    background: rgba(37, 99, 235, 0.08);
    color: var(--primary);
}

.faq-item.active .faq-question i {
    transform: rotate(180deg);
    color: var(--primary);
}

.faq-item i {
    color: var(--primary);
}

.article-list {
    display: grid;
    gap: 18px;
}

.article-card {
    background: var(--surface);
    padding: 22px;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
    display: grid;
    gap: 12px;
    transition: var(--transition);
}

.article-card__link {
    display: grid;
    gap: 12px;
    color: inherit;
}

.article-card__link:hover {
    color: inherit;
}

.article-card:hover {
    transform: translateY(-3px);
    box-shadow: 0 18px 28px rgba(15, 23, 42, 0.12);
}

.article-card__meta {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    font-size: 0.9rem;
    color: var(--muted);
}

.article-card__meta i {
    color: var(--primary);
}

.article-card__meta span {
    display: inline-flex;
    align-items: center;
    gap: 6px;
}

.article-card__title {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--text);
}

.article-card__excerpt {
    color: var(--text-light);
    font-size: 0.98rem;
}

.article-card__tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.pill-tag {
    background: var(--surface-alt);
    border: 1px solid rgba(37, 99, 235, 0.15);
    color: var(--primary);
    padding: 4px 12px;
    border-radius: 999px;
    font-size: 0.8rem;
}

.empty-state,
.error-state {
    text-align: center;
    padding: 48px 24px;
    color: var(--muted);
    background: var(--surface);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
}

.empty-state i,
.error-state i {
    font-size: 2.6rem;
    margin-bottom: 16px;
}

.site-footer {
    background: rgba(15, 23, 42, 0.94);
    color: rgba(226, 232, 240, 0.88);
    padding: 48px 0 64px;
    margin-top: auto;
}

.footer-grid {
    display: grid;
    gap: 24px;
}

.footer-meta {
    display: grid;
    gap: 12px;
}

.footer-meta .brand {
    color: white;
}

.footer-links {
    display: flex;
    flex-wrap: wrap;
    gap: 16px;
}

.footer-links a {
    color: rgba(226, 232, 240, 0.8);
    font-size: 0.92rem;
}

.footer-copy {
    font-size: 0.86rem;
    color: rgba(226, 232, 240, 0.65);
}

.mobile-footer {
    position: fixed;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--surface);
    display: flex;
    justify-content: space-around;
    padding: 10px 0 8px;
    box-shadow: 0 -6px 18px rgba(15, 23, 42, 0.12);
    z-index: 120;
}

.mobile-footer .footer-tab {
    display: inline-flex;
    flex-direction: column;
    align-items: center;
    gap: 6px;
    padding: 6px 12px;
    color: var(--muted);
    font-size: 0.8rem;
}

.mobile-footer .footer-tab i {
    font-size: 1.25rem;
}

.mobile-footer .footer-tab.active {
    color: var(--primary);
}

.mobile-footer .footer-tab:hover {
    color: var(--primary-dark);
}

.back-link {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    margin-top: 32px;
    padding: 12px 18px;
    background: var(--primary);
    color: white;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
}

.back-link:hover {
    transform: translateY(-2px);
}

.article-shell {
    background: var(--surface);
    border-radius: var(--radius-lg);
    padding: clamp(24px, 4vw, 40px);
    box-shadow: var(--shadow-md);
    display: grid;
    gap: 24px;
}

.article-shell header h1 {
    font-size: clamp(1.8rem, 4vw, 2.4rem);
    font-weight: 700;
    color: var(--text);
}

.article-meta-line {
    display: flex;
    flex-wrap: wrap;
    gap: 14px;
    font-size: 0.95rem;
    color: var(--muted);
}

.article-meta-line span[data-article-views] {
    color: var(--primary);
    font-weight: 600;
    margin-left: 4px;
}

.article-tags-line {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.article-excerpt {
    font-size: 1.05rem;
    color: var(--text-light);
    font-style: italic;
}

.article-content {
    display: grid;
    gap: 16px;
    color: var(--text);
}

.article-content h1,
.article-content h2,
.article-content h3,
.article-content h4 {
    color: var(--text);
    margin: 28px 0 12px;
    line-height: 1.3;
}

.article-content p {
    font-size: 1.02rem;
    color: var(--text-light);
}

.article-content ul,
.article-content ol {
    padding-left: 24px;
    display: grid;
    gap: 8px;
}

.article-content blockquote {
    border-left: 4px solid rgba(37, 99, 235, 0.5);
    padding-left: 20px;
    color: var(--text-light);
    background: rgba(37, 99, 235, 0.08);
    border-radius: 0 12px 12px 0;
}

.article-content code {
    background: rgba(15, 23, 42, 0.08);
    padding: 0.15em 0.4em;
    border-radius: 6px;
    font-family: 'Fira Code', 'Courier New', monospace;
}

.article-content pre {
    background: #0f172a;
    color: #e2e8f0;
    padding: 18px;
    border-radius: 14px;
    overflow-x: auto;
}

.article-content pre code {
    background: transparent;
    padding: 0;
}

.article-ad {
    border-radius: var(--radius-md);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    background: linear-gradient(135deg, #667eea, #764ba2);
}

.article-ad a {
    display: block;
    padding: 22px;
    color: white;
}

.article-ad a:hover {
    transform: translateY(-3px);
}

.article-ad h3 {
    font-size: 1.2rem;
    margin-bottom: 6px;
}

.breadcrumb {
    font-size: 0.9rem;
    color: var(--muted);
    display: inline-flex;
    align-items: center;
    gap: 10px;
}

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

.hidden {
    display: none !important;
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

.reveal {
    opacity: 0;
    transform: translateY(26px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.reveal.is-visible {
    opacity: 1;
    transform: translateY(0);
}

.button.is-clicked {
    transform: scale(0.98);
}

@media (max-width: 960px) {
    .primary-nav-list {
        position: absolute;
        top: 60px;
        right: 4%;
        background: var(--surface);
        padding: 16px;
        border-radius: var(--radius-md);
        box-shadow: var(--shadow-sm);
        flex-direction: column;
        align-items: flex-start;
        min-width: 210px;
        display: none;
    }

    .primary-nav-list.open {
        display: flex;
    }

    .nav-toggle {
        display: inline-flex;
    }
}

@media (max-width: 600px) {
    .site-main {
        padding-bottom: 96px;
    }

    .cta-group {
        flex-direction: column;
        align-items: stretch;
    }

    .hero-notice {
        flex-direction: column;
        align-items: flex-start;
        gap: 6px;
    }

    .article-card {
        padding: 20px 18px;
    }

    .article-shell {
        padding: 22px 18px;
    }

    .site-footer {
        padding: 36px 0 88px;
    }
}