:root {
    --canvas: #f7f7f4;
    --canvas-soft: #fafaf7;
    --surface-card: #ffffff;
    --surface-strong: #e6e5e0;
    --primary: #f54e00;
    --primary-active: #d04200;
    --ink: #26251e;
    --body: #5a5852;
    --body-strong: #26251e;
    --muted: #807d72;
    --muted-soft: #a09c92;
    --on-primary: #ffffff;
    --hairline: #e6e5e0;
    --hairline-soft: #efeee8;
    --hairline-strong: #cfcdc4;
    --semantic-success: #1f8a65;
    --semantic-error: #cf2d56;
    --radius-xs: 4px;
    --radius-sm: 6px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    --radius-pill: 9999px;
    --font-sans: 'Inter', system-ui, 'Helvetica Neue', Helvetica, Arial, sans-serif;
    --font-mono: 'JetBrains Mono', monospace;
    --section: 80px;
}

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

html { font-size: 16px; scroll-behavior: smooth; }

body {
    font-family: var(--font-sans);
    font-size: 16px;
    font-weight: 400;
    line-height: 1.5;
    color: var(--body);
    background: var(--canvas);
    -webkit-font-smoothing: antialiased;
}

a { color: var(--ink); text-decoration: none; }
a:hover { color: var(--primary); }

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

ul, ol { list-style: none; }

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

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

.nav-inner {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
    height: 64px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 32px;
}

.nav-logo {
    font-size: 18px;
    font-weight: 600;
    color: var(--ink);
    letter-spacing: -0.3px;
    flex-shrink: 0;
}

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

.nav-menu {
    display: flex;
    align-items: center;
    gap: 32px;
}

.nav-menu a {
    font-size: 14px;
    font-weight: 500;
    color: var(--body);
    line-height: 1.4;
    transition: color 0.15s;
}

.nav-menu a:hover,
.nav-menu a[aria-current="page"] { color: var(--ink); }

.nav-toggle {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    width: 40px;
    height: 40px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
}

.nav-toggle span {
    display: block;
    width: 22px;
    height: 2px;
    background: var(--ink);
    transition: transform 0.2s, opacity 0.2s;
}

.site-hero {
    padding: var(--section) 0 60px;
    border-bottom: 1px solid var(--hairline);
}

.hero-inner {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 64px;
    align-items: start;
}

.hero-label {
    display: inline-block;
    font-size: 11px;
    font-weight: 600;
    letter-spacing: 0.88px;
    text-transform: uppercase;
    color: var(--muted);
    margin-bottom: 20px;
    background: var(--surface-strong);
    padding: 4px 10px;
    border-radius: var(--radius-pill);
}

.hero-title {
    font-size: 48px;
    font-weight: 400;
    line-height: 1.1;
    letter-spacing: -1.2px;
    color: var(--ink);
    margin-bottom: 20px;
}

.hero-desc {
    font-size: 16px;
    line-height: 1.6;
    color: var(--body);
    max-width: 480px;
    margin-bottom: 32px;
}

.hero-meta {
    font-size: 13px;
    color: var(--muted);
}

.hero-image {
    border-radius: var(--radius-lg);
    overflow: hidden;
    border: 1px solid var(--hairline);
}

.hero-image img {
    width: 100%;
    height: 360px;
    object-fit: cover;
}

.section {
    padding: var(--section) 0;
}

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

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

.section-title {
    font-size: 36px;
    font-weight: 400;
    letter-spacing: -0.72px;
    color: var(--ink);
    line-height: 1.2;
    margin-bottom: 16px;
}

.section-desc {
    font-size: 16px;
    line-height: 1.6;
    color: var(--body);
    max-width: 640px;
    margin-bottom: 48px;
}

.articles-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.article-card {
    background: var(--surface-card);
    border: 1px solid var(--hairline);
    border-radius: var(--radius-lg);
    overflow: hidden;
    transition: border-color 0.15s;
}

.article-card:hover { border-color: var(--hairline-strong); }

.article-card-img {
    width: 100%;
    height: 200px;
    object-fit: cover;
}

.article-card-body {
    padding: 24px;
}

.article-card-tag {
    font-size: 11px;
    font-weight: 600;
    letter-spacing: 0.88px;
    text-transform: uppercase;
    color: var(--muted);
    margin-bottom: 10px;
    display: block;
}

.article-card-title {
    font-size: 18px;
    font-weight: 600;
    color: var(--ink);
    line-height: 1.3;
    margin-bottom: 10px;
}

.article-card-title a { color: var(--ink); }
.article-card-title a:hover { color: var(--primary); }

.article-card-excerpt {
    font-size: 14px;
    line-height: 1.6;
    color: var(--body);
    margin-bottom: 20px;
}

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

.info-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
    margin-top: 48px;
}

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

.info-card-title {
    font-size: 18px;
    font-weight: 600;
    color: var(--ink);
    margin-bottom: 12px;
}

.info-card-text {
    font-size: 14px;
    line-height: 1.6;
    color: var(--body);
}

.divider {
    border: none;
    border-top: 1px solid var(--hairline);
}

.article-page {
    max-width: 1200px;
    margin: 0 auto;
    padding: 64px 24px;
    display: grid;
    grid-template-columns: 1fr 300px;
    gap: 64px;
    align-items: start;
}

.article-content h1 {
    font-size: 40px;
    font-weight: 400;
    letter-spacing: -0.8px;
    color: var(--ink);
    line-height: 1.15;
    margin-bottom: 16px;
}

.article-content .article-meta {
    font-size: 13px;
    color: var(--muted);
    margin-bottom: 32px;
    display: flex;
    gap: 16px;
    flex-wrap: wrap;
}

.article-content .article-lead {
    font-size: 18px;
    line-height: 1.6;
    color: var(--body-strong);
    margin-bottom: 32px;
    padding-bottom: 32px;
    border-bottom: 1px solid var(--hairline);
}

.article-content h2 {
    font-size: 26px;
    font-weight: 400;
    letter-spacing: -0.325px;
    color: var(--ink);
    margin: 40px 0 16px;
}

.article-content h3 {
    font-size: 18px;
    font-weight: 600;
    color: var(--ink);
    margin: 28px 0 12px;
}

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

.article-content ul,
.article-content ol {
    padding-left: 20px;
    margin-bottom: 20px;
}

.article-content ul { list-style: disc; }
.article-content ol { list-style: decimal; }

.article-content li {
    font-size: 16px;
    line-height: 1.7;
    color: var(--body);
    margin-bottom: 6px;
}

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

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

.article-content .info-box {
    background: var(--surface-card);
    border: 1px solid var(--hairline);
    border-radius: var(--radius-lg);
    padding: 24px;
    margin: 32px 0;
}

.article-content .info-box h4 {
    font-size: 16px;
    font-weight: 600;
    color: var(--ink);
    margin-bottom: 12px;
}

.article-content .info-box p,
.article-content .info-box li {
    font-size: 14px;
}

.article-content .code-formula {
    font-family: var(--font-mono);
    font-size: 13px;
    background: var(--surface-card);
    border: 1px solid var(--hairline);
    border-radius: var(--radius-lg);
    padding: 20px;
    overflow-x: auto;
    margin: 24px 0;
    color: var(--ink);
    line-height: 1.6;
}

.article-sidebar {
    position: sticky;
    top: 80px;
}

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

.sidebar-card-title {
    font-size: 14px;
    font-weight: 600;
    color: var(--ink);
    margin-bottom: 16px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    font-size: 11px;
}

.sidebar-card ul li {
    margin-bottom: 10px;
}

.sidebar-card ul li a {
    font-size: 14px;
    color: var(--body);
    line-height: 1.4;
}

.sidebar-card ul li a:hover { color: var(--primary); }

.sidebar-card .sidebar-updated {
    font-size: 12px;
    color: var(--muted);
    margin-top: 12px;
}

.page-content {
    max-width: 800px;
    margin: 0 auto;
    padding: 64px 24px;
}

.page-content h1 {
    font-size: 40px;
    font-weight: 400;
    letter-spacing: -0.8px;
    color: var(--ink);
    margin-bottom: 12px;
}

.page-content .page-updated {
    font-size: 13px;
    color: var(--muted);
    margin-bottom: 40px;
}

.page-content h2 {
    font-size: 26px;
    font-weight: 400;
    letter-spacing: -0.325px;
    color: var(--ink);
    margin: 40px 0 16px;
}

.page-content h3 {
    font-size: 18px;
    font-weight: 600;
    color: var(--ink);
    margin: 28px 0 12px;
}

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

.page-content ul {
    list-style: disc;
    padding-left: 20px;
    margin-bottom: 20px;
}

.page-content li {
    font-size: 16px;
    line-height: 1.7;
    color: var(--body);
    margin-bottom: 6px;
}

.contact-form-wrap {
    background: var(--surface-card);
    border: 1px solid var(--hairline);
    border-radius: var(--radius-lg);
    padding: 40px;
    margin-top: 48px;
}

.contact-form-wrap h2 {
    font-size: 26px;
    font-weight: 400;
    letter-spacing: -0.325px;
    color: var(--ink);
    margin-bottom: 24px;
}

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

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

.form-group input,
.form-group textarea {
    width: 100%;
    background: var(--canvas-soft);
    border: 1px solid var(--hairline-strong);
    border-radius: var(--radius-md);
    padding: 12px 16px;
    height: 44px;
    font-family: var(--font-sans);
    font-size: 16px;
    color: var(--ink);
    outline: none;
    transition: border-color 0.15s;
}

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

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

.form-group input::placeholder,
.form-group textarea::placeholder {
    color: var(--muted-soft);
}

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

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

.btn-secondary {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    height: 40px;
    padding: 10px 18px;
    background: var(--surface-card);
    color: var(--ink);
    font-family: var(--font-sans);
    font-size: 14px;
    font-weight: 500;
    border: 1px solid var(--hairline-strong);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: border-color 0.15s;
    text-decoration: none;
}

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

.form-message {
    display: none;
    margin-top: 16px;
    padding: 12px 16px;
    border-radius: var(--radius-md);
    font-size: 14px;
    font-weight: 500;
}

.form-message.success {
    background: #e8f5f1;
    color: var(--semantic-success);
    border: 1px solid #b8ddd3;
}

.form-message.error {
    background: #fdeef2;
    color: var(--semantic-error);
    border: 1px solid #f4c0cc;
}

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

.footer-inner {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 48px;
}

.footer-logo {
    font-size: 18px;
    font-weight: 600;
    color: var(--ink);
    display: block;
    margin-bottom: 12px;
}

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

.footer-tagline {
    font-size: 14px;
    line-height: 1.6;
    color: var(--body);
    max-width: 280px;
}

.footer-col-label {
    font-size: 11px;
    font-weight: 600;
    letter-spacing: 0.88px;
    text-transform: uppercase;
    color: var(--muted);
    margin-bottom: 16px;
}

.footer-col ul li {
    margin-bottom: 10px;
}

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

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

.footer-bottom {
    max-width: 1200px;
    margin: 48px auto 0;
    padding: 24px 24px 0;
    border-top: 1px solid var(--hairline);
}

.footer-bottom p {
    font-size: 13px;
    color: var(--muted);
}

.cookie-banner {
    display: none;
    position: fixed;
    bottom: 24px;
    left: 24px;
    right: 24px;
    max-width: 600px;
    background: var(--surface-card);
    border: 1px solid var(--hairline-strong);
    border-radius: var(--radius-lg);
    padding: 20px 24px;
    z-index: 999;
    box-shadow: 0 2px 16px rgba(38,37,30,0.08);
}

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

.cookie-inner p {
    font-size: 14px;
    color: var(--body);
    line-height: 1.5;
    margin-bottom: 16px;
}

.cookie-inner p a { color: var(--ink); text-decoration: underline; }

.cookie-actions {
    display: flex;
    gap: 12px;
}

.breadcrumb {
    font-size: 13px;
    color: var(--muted);
    margin-bottom: 32px;
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
}

.breadcrumb a { color: var(--muted); }
.breadcrumb a:hover { color: var(--ink); }
.breadcrumb span { color: var(--muted-soft); }

.articles-list-page {
    max-width: 1200px;
    margin: 0 auto;
    padding: 64px 24px;
}

@media (max-width: 1024px) {
    .hero-inner { grid-template-columns: 1fr; gap: 40px; }
    .hero-title { font-size: 40px; }
    .articles-grid { grid-template-columns: repeat(2, 1fr); }
    .info-grid { grid-template-columns: repeat(2, 1fr); }
    .footer-inner { grid-template-columns: 1fr 1fr; gap: 32px; }
    .article-page { grid-template-columns: 1fr; }
    .article-sidebar { position: static; }
}

@media (max-width: 768px) {
    .nav-menu {
        display: none;
        position: absolute;
        top: 64px;
        left: 0;
        right: 0;
        background: var(--canvas);
        border-bottom: 1px solid var(--hairline);
        flex-direction: column;
        padding: 16px 24px;
        gap: 0;
    }

    .nav-menu.open { display: flex; }
    .nav-menu li { width: 100%; }
    .nav-menu a { display: block; padding: 12px 0; border-bottom: 1px solid var(--hairline-soft); }
    .nav-toggle { display: flex; }
    .site-nav { position: relative; }
    .hero-title { font-size: 32px; letter-spacing: -0.5px; }
    .section-title { font-size: 28px; }
    .articles-grid { grid-template-columns: 1fr; }
    .info-grid { grid-template-columns: 1fr; }
    .footer-inner { grid-template-columns: 1fr; gap: 32px; }
    .cookie-banner { left: 12px; right: 12px; bottom: 12px; }
    .contact-form-wrap { padding: 24px; }
    .article-content h1 { font-size: 30px; }
    .page-content h1 { font-size: 30px; }
}

@media (max-width: 640px) {
    .hero-title { font-size: 28px; }
}