@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600&family=JetBrains+Mono:wght@400&display=swap');

:root {
    --color-canvas: #f7f7f4;
    --color-canvas-soft: #fafaf7;
    --color-surface-card: #ffffff;
    --color-surface-strong: #e6e5e0;
    --color-primary: #f54e00;
    --color-primary-active: #d04200;
    --color-ink: #26251e;
    --color-body: #5a5852;
    --color-body-strong: #26251e;
    --color-muted: #807d72;
    --color-muted-soft: #a09c92;
    --color-on-primary: #ffffff;
    --color-hairline: #e6e5e0;
    --color-hairline-soft: #efeee8;
    --color-hairline-strong: #cfcdc4;
    --color-semantic-success: #1f8a65;
    --color-semantic-error: #cf2d56;
    --rounded-xs: 4px;
    --rounded-sm: 6px;
    --rounded-md: 8px;
    --rounded-lg: 12px;
    --rounded-xl: 16px;
    --rounded-pill: 9999px;
}

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

html { scroll-behavior: smooth; }

body {
    font-family: 'Inter', system-ui, "Helvetica Neue", Helvetica, Arial, sans-serif;
    font-size: 16px;
    font-weight: 400;
    line-height: 1.5;
    color: var(--color-body);
    background-color: var(--color-canvas);
}

a { color: inherit; text-decoration: none; }
a:hover { color: var(--color-ink); }
img { max-width: 100%; height: auto; display: block; }
ul, ol { list-style: none; }

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

h1, h2, h3, h4 {
    color: var(--color-ink);
    font-weight: 400;
    line-height: 1.2;
    letter-spacing: -0.5px;
}

h1 { font-size: 48px; letter-spacing: -1.2px; }
h2 { font-size: 36px; letter-spacing: -0.72px; }
h3 { font-size: 26px; letter-spacing: -0.325px; }
h4 { font-size: 22px; letter-spacing: -0.11px; }

p { margin-bottom: 16px; }
p:last-child { margin-bottom: 0; }

.text-muted { color: var(--color-muted); }
.text-body { color: var(--color-body); }
.text-ink { color: var(--color-ink); }

.badge {
    display: inline-flex;
    align-items: center;
    background: var(--color-surface-strong);
    color: var(--color-ink);
    font-size: 11px;
    font-weight: 600;
    line-height: 1.4;
    letter-spacing: 0.88px;
    text-transform: uppercase;
    border-radius: var(--rounded-pill);
    padding: 4px 10px;
}

.btn-primary {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    background: var(--color-primary);
    color: var(--color-on-primary);
    font-size: 14px;
    font-weight: 500;
    line-height: 1;
    padding: 10px 18px;
    height: 40px;
    border-radius: var(--rounded-md);
    border: none;
    cursor: pointer;
    transition: background 0.15s ease;
}

.btn-primary:hover { background: var(--color-primary-active); color: var(--color-on-primary); }

.btn-secondary {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    background: var(--color-surface-card);
    color: var(--color-ink);
    font-size: 14px;
    font-weight: 500;
    line-height: 1;
    padding: 10px 18px;
    height: 40px;
    border-radius: var(--rounded-md);
    border: 1px solid var(--color-hairline-strong);
    cursor: pointer;
    transition: border-color 0.15s ease;
}

.btn-secondary:hover { border-color: var(--color-ink); color: var(--color-ink); }

.site-header {
    background: var(--color-canvas);
    border-bottom: 1px solid var(--color-hairline);
    height: 64px;
    position: sticky;
    top: 0;
    z-index: 100;
}

.site-header .container {
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 24px;
}

.site-logo {
    font-size: 18px;
    font-weight: 600;
    color: var(--color-ink);
    letter-spacing: -0.3px;
    white-space: nowrap;
}

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

.site-nav {
    display: flex;
    align-items: center;
    gap: 8px;
}

.site-nav a {
    font-size: 14px;
    font-weight: 500;
    color: var(--color-body);
    padding: 6px 12px;
    border-radius: var(--rounded-sm);
    transition: color 0.15s ease, background 0.15s ease;
}

.site-nav a:hover, .site-nav a.active {
    color: var(--color-ink);
    background: var(--color-surface-strong);
}

.nav-hamburger {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
    color: var(--color-ink);
}

.nav-hamburger svg { display: block; }

.hero-section {
    padding: 80px 0;
    border-bottom: 1px solid var(--color-hairline);
}

.hero-content {
    max-width: 720px;
}

.hero-content .badge { margin-bottom: 20px; }

.hero-content h1 {
    font-size: 56px;
    letter-spacing: -1.5px;
    margin-bottom: 20px;
    color: var(--color-ink);
}

.hero-content p {
    font-size: 18px;
    line-height: 1.6;
    color: var(--color-body);
    margin-bottom: 32px;
    max-width: 560px;
}

.hero-image {
    margin-top: 48px;
    border-radius: var(--rounded-lg);
    overflow: hidden;
    border: 1px solid var(--color-hairline);
    background: var(--color-surface-card);
}

.hero-image img {
    width: 100%;
    height: 420px;
    object-fit: cover;
}

.section { padding: 80px 0; }
.section-alt { background: var(--color-canvas-soft); }

.section-label {
    font-size: 11px;
    font-weight: 600;
    letter-spacing: 0.88px;
    text-transform: uppercase;
    color: var(--color-muted);
    margin-bottom: 12px;
}

.section-title {
    font-size: 36px;
    font-weight: 400;
    letter-spacing: -0.72px;
    color: var(--color-ink);
    margin-bottom: 16px;
}

.section-desc {
    font-size: 16px;
    color: var(--color-body);
    max-width: 560px;
    margin-bottom: 48px;
    line-height: 1.6;
}

.grid-3 {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
}

.grid-2 {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 20px;
}

.card {
    background: var(--color-surface-card);
    border: 1px solid var(--color-hairline);
    border-radius: var(--rounded-lg);
    padding: 24px;
}

.card-img {
    width: 100%;
    height: 200px;
    object-fit: cover;
    border-radius: var(--rounded-md);
    margin-bottom: 20px;
}

.card-label {
    font-size: 11px;
    font-weight: 600;
    letter-spacing: 0.88px;
    text-transform: uppercase;
    color: var(--color-muted);
    margin-bottom: 8px;
}

.card h3 {
    font-size: 20px;
    font-weight: 600;
    letter-spacing: -0.2px;
    color: var(--color-ink);
    margin-bottom: 10px;
}

.card p {
    font-size: 14px;
    line-height: 1.6;
    color: var(--color-body);
    margin-bottom: 16px;
}

.card-link {
    font-size: 14px;
    font-weight: 500;
    color: var(--color-primary);
    transition: color 0.15s ease;
}

.card-link:hover { color: var(--color-primary-active); }

.article-card {
    background: var(--color-surface-card);
    border: 1px solid var(--color-hairline);
    border-radius: var(--rounded-lg);
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

.article-card-img {
    width: 100%;
    height: 220px;
    object-fit: cover;
}

.article-card-body {
    padding: 24px;
    flex: 1;
    display: flex;
    flex-direction: column;
}

.article-card-body .badge { margin-bottom: 12px; }

.article-card-body h3 {
    font-size: 20px;
    font-weight: 600;
    letter-spacing: -0.2px;
    color: var(--color-ink);
    margin-bottom: 10px;
    line-height: 1.3;
}

.article-card-body p {
    font-size: 14px;
    color: var(--color-body);
    line-height: 1.6;
    flex: 1;
}

.article-card-footer {
    padding: 16px 24px;
    border-top: 1px solid var(--color-hairline);
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.article-card-date {
    font-size: 13px;
    color: var(--color-muted);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1px;
    background: var(--color-hairline);
    border: 1px solid var(--color-hairline);
    border-radius: var(--rounded-lg);
    overflow: hidden;
}

.feature-item {
    background: var(--color-surface-card);
    padding: 28px 24px;
}

.feature-icon {
    width: 40px;
    height: 40px;
    border-radius: var(--rounded-md);
    background: var(--color-surface-strong);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 16px;
    color: var(--color-ink);
}

.feature-item h4 {
    font-size: 16px;
    font-weight: 600;
    color: var(--color-ink);
    margin-bottom: 8px;
    letter-spacing: 0;
}

.feature-item p {
    font-size: 14px;
    color: var(--color-body);
    line-height: 1.6;
    margin: 0;
}

.article-hero {
    padding: 64px 0 48px;
    border-bottom: 1px solid var(--color-hairline);
}

.article-hero .badge { margin-bottom: 16px; }

.article-hero h1 {
    font-size: 44px;
    letter-spacing: -1px;
    margin-bottom: 16px;
    max-width: 760px;
}

.article-meta {
    display: flex;
    align-items: center;
    gap: 20px;
    font-size: 14px;
    color: var(--color-muted);
    margin-top: 20px;
}

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

.article-body {
    padding: 48px 0 80px;
}

.article-body .content-area {
    max-width: 760px;
}

.article-body h2 {
    font-size: 28px;
    font-weight: 600;
    letter-spacing: -0.4px;
    color: var(--color-ink);
    margin: 40px 0 16px;
}

.article-body h2:first-child { margin-top: 0; }

.article-body h3 {
    font-size: 20px;
    font-weight: 600;
    letter-spacing: -0.2px;
    color: var(--color-ink);
    margin: 28px 0 12px;
}

.article-body p {
    font-size: 16px;
    line-height: 1.7;
    color: var(--color-body);
    margin-bottom: 20px;
}

.article-body ul, .article-body ol {
    list-style: none;
    margin: 0 0 20px 0;
    padding: 0;
}

.article-body ul li, .article-body ol li {
    font-size: 16px;
    line-height: 1.7;
    color: var(--color-body);
    padding-left: 20px;
    position: relative;
    margin-bottom: 8px;
}

.article-body ul li::before {
    content: '—';
    position: absolute;
    left: 0;
    color: var(--color-muted);
}

.article-body ol {
    counter-reset: list-counter;
}

.article-body ol li {
    counter-increment: list-counter;
}

.article-body ol li::before {
    content: counter(list-counter) '.';
    position: absolute;
    left: 0;
    color: var(--color-muted);
    font-weight: 600;
}

.article-body .article-img {
    width: 100%;
    border-radius: var(--rounded-lg);
    border: 1px solid var(--color-hairline);
    margin: 32px 0;
}

.article-body .img-caption {
    font-size: 13px;
    color: var(--color-muted);
    text-align: center;
    margin-top: -24px;
    margin-bottom: 32px;
}

.info-box {
    background: var(--color-surface-card);
    border: 1px solid var(--color-hairline);
    border-left: 3px solid var(--color-primary);
    border-radius: var(--rounded-md);
    padding: 20px 24px;
    margin: 28px 0;
}

.info-box p { margin: 0; font-size: 15px; }

.table-wrapper {
    overflow-x: auto;
    margin: 28px 0;
}

.data-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 14px;
}

.data-table th, .data-table td {
    padding: 12px 16px;
    text-align: left;
    border-bottom: 1px solid var(--color-hairline);
}

.data-table th {
    font-weight: 600;
    color: var(--color-ink);
    background: var(--color-surface-strong);
    font-size: 12px;
    letter-spacing: 0.5px;
    text-transform: uppercase;
}

.data-table td { color: var(--color-body); }

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

.related-articles {
    border-top: 1px solid var(--color-hairline);
    padding-top: 48px;
    margin-top: 48px;
}

.related-articles h2 { margin-bottom: 28px; font-size: 24px; font-weight: 600; }

.contact-section { padding: 80px 0; background: var(--color-canvas-soft); }

.contact-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 48px;
    align-items: start;
}

.contact-info h2 {
    font-size: 36px;
    font-weight: 400;
    letter-spacing: -0.72px;
    color: var(--color-ink);
    margin-bottom: 16px;
}

.contact-info p { font-size: 16px; line-height: 1.6; margin-bottom: 32px; }

.contact-detail {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.contact-detail-item {
    display: flex;
    align-items: flex-start;
    gap: 12px;
    font-size: 14px;
    color: var(--color-body);
}

.contact-detail-item svg { flex-shrink: 0; margin-top: 2px; color: var(--color-muted); }

.contact-form-wrap {
    background: var(--color-surface-card);
    border: 1px solid var(--color-hairline);
    border-radius: var(--rounded-lg);
    padding: 32px;
}

.form-group { margin-bottom: 20px; }

.form-group label {
    display: block;
    font-size: 14px;
    font-weight: 500;
    color: var(--color-ink);
    margin-bottom: 6px;
}

.form-group input, .form-group textarea, .form-group select {
    width: 100%;
    background: var(--color-surface-card);
    color: var(--color-ink);
    font-family: inherit;
    font-size: 16px;
    font-weight: 400;
    line-height: 1.5;
    border: 1px solid var(--color-hairline-strong);
    border-radius: var(--rounded-md);
    padding: 12px 16px;
    height: 44px;
    transition: border-color 0.15s ease;
    outline: none;
}

.form-group textarea {
    height: auto;
    min-height: 120px;
    resize: vertical;
}

.form-group input:focus, .form-group textarea:focus {
    border-color: var(--color-ink);
}

.form-group input.error, .form-group textarea.error {
    border-color: var(--color-semantic-error);
}

.form-error-msg {
    font-size: 13px;
    color: var(--color-semantic-error);
    margin-top: 4px;
    display: none;
}

.form-success {
    background: #f0faf6;
    border: 1px solid #c3e6d8;
    border-radius: var(--rounded-md);
    padding: 16px 20px;
    font-size: 15px;
    color: var(--color-semantic-success);
    display: none;
    margin-bottom: 20px;
}

.btn-submit {
    width: 100%;
    background: var(--color-ink);
    color: var(--color-canvas);
    font-size: 14px;
    font-weight: 500;
    padding: 12px 20px;
    height: 44px;
    border-radius: var(--rounded-md);
    border: none;
    cursor: pointer;
    transition: opacity 0.15s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
}

.btn-submit:hover { opacity: 0.85; }
.btn-submit:disabled { opacity: 0.6; cursor: not-allowed; }

.spinner {
    width: 16px;
    height: 16px;
    border: 2px solid rgba(255,255,255,0.3);
    border-top-color: #fff;
    border-radius: 50%;
    animation: spin 0.6s linear infinite;
    display: none;
}

@keyframes spin { to { transform: rotate(360deg); } }

.site-footer {
    background: var(--color-canvas);
    border-top: 1px solid var(--color-hairline);
    padding: 64px 0 48px;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr 1fr;
    gap: 40px;
    margin-bottom: 48px;
}

.footer-brand p {
    font-size: 14px;
    color: var(--color-body);
    line-height: 1.6;
    margin-top: 12px;
    max-width: 240px;
}

.footer-col h4 {
    font-size: 13px;
    font-weight: 600;
    color: var(--color-ink);
    letter-spacing: 0.5px;
    text-transform: uppercase;
    margin-bottom: 16px;
}

.footer-col ul { display: flex; flex-direction: column; gap: 10px; }

.footer-col ul li a {
    font-size: 14px;
    color: var(--color-body);
    transition: color 0.15s ease;
}

.footer-col ul li a:hover { color: var(--color-ink); }

.footer-bottom {
    border-top: 1px solid var(--color-hairline);
    padding-top: 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: 13px;
    color: var(--color-muted);
}

.footer-bottom a { color: var(--color-muted); }
.footer-bottom a:hover { color: var(--color-ink); }

.breadcrumb {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 13px;
    color: var(--color-muted);
    margin-bottom: 24px;
}

.breadcrumb a { color: var(--color-muted); }
.breadcrumb a:hover { color: var(--color-ink); }
.breadcrumb-sep { color: var(--color-hairline-strong); }

.page-hero {
    padding: 64px 0 56px;
    border-bottom: 1px solid var(--color-hairline);
}

.page-hero h1 { font-size: 44px; letter-spacing: -1px; margin-bottom: 16px; }
.page-hero p { font-size: 18px; max-width: 600px; }

.page-content { padding: 64px 0 80px; }

.page-content .prose {
    max-width: 800px;
}

.page-content .prose h2 {
    font-size: 26px;
    font-weight: 600;
    letter-spacing: -0.3px;
    color: var(--color-ink);
    margin: 40px 0 14px;
    border-bottom: 1px solid var(--color-hairline);
    padding-bottom: 10px;
}

.page-content .prose h2:first-child { margin-top: 0; }

.page-content .prose h3 {
    font-size: 20px;
    font-weight: 600;
    color: var(--color-ink);
    margin: 28px 0 10px;
}

.page-content .prose p {
    font-size: 16px;
    line-height: 1.7;
    color: var(--color-body);
    margin-bottom: 18px;
}

.page-content .prose ul {
    list-style: none;
    margin: 0 0 18px;
}

.page-content .prose ul li {
    font-size: 16px;
    line-height: 1.7;
    color: var(--color-body);
    padding-left: 20px;
    position: relative;
    margin-bottom: 8px;
}

.page-content .prose ul li::before {
    content: '—';
    position: absolute;
    left: 0;
    color: var(--color-muted);
}

.page-content .prose a { color: var(--color-primary); }
.page-content .prose a:hover { color: var(--color-primary-active); }

.cookie-banner {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: var(--color-ink);
    color: var(--color-canvas);
    padding: 20px 24px;
    z-index: 200;
    display: none;
}

.cookie-banner.visible { display: block; }

.cookie-inner {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 24px;
    flex-wrap: wrap;
}

.cookie-text { font-size: 14px; line-height: 1.6; flex: 1; min-width: 200px; }
.cookie-text a { color: var(--color-canvas); text-decoration: underline; }

.cookie-actions { display: flex; gap: 10px; flex-shrink: 0; }

.cookie-accept {
    background: var(--color-primary);
    color: #fff;
    font-size: 14px;
    font-weight: 500;
    padding: 8px 18px;
    height: 36px;
    border-radius: var(--rounded-md);
    border: none;
    cursor: pointer;
}

.cookie-reject {
    background: transparent;
    color: var(--color-canvas);
    font-size: 14px;
    font-weight: 500;
    padding: 8px 18px;
    height: 36px;
    border-radius: var(--rounded-md);
    border: 1px solid rgba(255,255,255,0.3);
    cursor: pointer;
}

.divider {
    height: 1px;
    background: var(--color-hairline);
    margin: 0;
}

.toc-sidebar {
    position: sticky;
    top: 80px;
    padding: 20px 24px;
    background: var(--color-surface-card);
    border: 1px solid var(--color-hairline);
    border-radius: var(--rounded-lg);
}

.toc-sidebar h4 {
    font-size: 12px;
    font-weight: 600;
    letter-spacing: 0.88px;
    text-transform: uppercase;
    color: var(--color-muted);
    margin-bottom: 16px;
}

.toc-list { display: flex; flex-direction: column; gap: 4px; }

.toc-list a {
    font-size: 14px;
    color: var(--color-body);
    padding: 4px 0;
    border-left: 2px solid transparent;
    padding-left: 12px;
    transition: color 0.15s ease, border-color 0.15s ease;
}

.toc-list a:hover, .toc-list a.active {
    color: var(--color-ink);
    border-left-color: var(--color-primary);
}

.article-layout {
    display: grid;
    grid-template-columns: 1fr 280px;
    gap: 48px;
    align-items: start;
}

@media (max-width: 1024px) {
    h1 { font-size: 40px; }
    .hero-content h1 { font-size: 44px; }
    .section-title { font-size: 30px; }
    .grid-3 { grid-template-columns: repeat(2, 1fr); }
    .features-grid { grid-template-columns: repeat(2, 1fr); }
    .footer-grid { grid-template-columns: 1fr 1fr; gap: 32px; }
    .footer-brand { grid-column: 1 / -1; }
    .article-layout { grid-template-columns: 1fr; }
    .toc-sidebar { display: none; }
    .contact-grid { grid-template-columns: 1fr; gap: 32px; }
}

@media (max-width: 768px) {
    .site-nav { display: none; }
    .site-nav.open {
        display: flex;
        flex-direction: column;
        position: fixed;
        top: 64px;
        left: 0;
        right: 0;
        background: var(--color-canvas);
        border-bottom: 1px solid var(--color-hairline);
        padding: 16px 24px;
        gap: 4px;
        z-index: 99;
    }
    .site-nav.open a { padding: 10px 12px; border-radius: var(--rounded-md); }
    .nav-hamburger { display: flex; }
    .hero-content h1 { font-size: 36px; letter-spacing: -0.8px; }
    .section-title { font-size: 26px; }
    .grid-3 { grid-template-columns: 1fr; }
    .grid-2 { grid-template-columns: 1fr; }
    .features-grid { grid-template-columns: 1fr; }
    .footer-grid { grid-template-columns: 1fr 1fr; }
    .page-hero h1 { font-size: 32px; }
    .article-hero h1 { font-size: 32px; }
    h1 { font-size: 32px; }
    h2 { font-size: 26px; }
    h3 { font-size: 22px; }
    .section { padding: 56px 0; }
    .hero-section { padding: 56px 0; }
    .footer-bottom { flex-direction: column; gap: 12px; text-align: center; }
}

@media (max-width: 480px) {
    .footer-grid { grid-template-columns: 1fr; }
    .hero-image img { height: 240px; }
    .cookie-inner { flex-direction: column; align-items: flex-start; }
}