:root {
    --color-primary: #c7000b;
    --color-primary-dark: #9e0009;
    --color-bg: #0f1117;
    --color-surface: #1a1d27;
    --color-surface-hover: #242836;
    --color-text: #e4e6eb;
    --color-text-muted: #9499a8;
    --color-border: #2d3140;
    --color-good: #2ecc71;
    --color-bad: #e74c3c;
    --radius: 8px;
    --max-width: 1100px;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background: var(--color-bg);
    color: var(--color-text);
    line-height: 1.6;
    min-height: 100vh;
}

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

code {
    background: var(--color-surface-hover);
    padding: 0.15em 0.4em;
    border-radius: 4px;
    font-size: 0.9em;
}

.navbar {
    background: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
    padding: 0 1.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 56px;
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-brand {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 700;
    font-size: 1.1rem;
    color: var(--color-text);
}

.nav-logo { width: 28px; height: 28px; }

.nav-links {
    display: flex;
    list-style: none;
    gap: 1.5rem;
}

.nav-links a {
    color: var(--color-text-muted);
    font-size: 0.95rem;
    transition: color 0.2s;
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--color-text);
    text-decoration: none;
}

.nav-links a.active {
    border-bottom: 2px solid var(--color-primary);
    padding-bottom: 2px;
}

.hero {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 4rem 1.5rem 3rem;
    display: flex;
    align-items: center;
    gap: 3rem;
}

.hero-content { flex: 1.2; }
.hero-visual { flex: 1; }

.hero h1 {
    font-size: 2.4rem;
    line-height: 1.2;
    margin-bottom: 1rem;
}

.highlight { color: var(--color-primary); }

.hero p {
    color: var(--color-text-muted);
    font-size: 1.1rem;
    margin-bottom: 1.5rem;
}

.hero-buttons { display: flex; gap: 1rem; flex-wrap: wrap; }

.btn {
    display: inline-block;
    padding: 0.65rem 1.4rem;
    border-radius: var(--radius);
    font-weight: 600;
    font-size: 0.95rem;
    transition: background 0.2s, transform 0.1s;
    text-decoration: none;
}

.btn:active { transform: scale(0.97); }

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

.btn-primary:hover {
    background: var(--color-primary-dark);
    text-decoration: none;
}

.btn-secondary {
    background: var(--color-surface-hover);
    color: var(--color-text);
    border: 1px solid var(--color-border);
}

.btn-secondary:hover {
    background: var(--color-border);
    text-decoration: none;
}

.architecture-diagram {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 2rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.8rem;
}

.arch-node {
    padding: 0.8rem 1.5rem;
    border-radius: var(--radius);
    font-weight: 600;
    text-align: center;
}

#user {
    background: var(--color-surface-hover);
    border: 1px solid var(--color-border);
}

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

.arch-arrow {
    font-size: 0.85rem;
    color: var(--color-text-muted);
    letter-spacing: 0.1em;
}

.arch-label {
    font-size: 0.8rem;
    color: var(--color-text-muted);
    font-family: monospace;
}

.features-grid {
    max-width: var(--max-width);
    margin: 0 auto 3rem;
    padding: 0 1.5rem;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 1.2rem;
}

.feature-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 1.5rem;
    transition: border-color 0.2s, transform 0.2s;
}

.feature-card:hover {
    border-color: var(--color-primary);
    transform: translateY(-2px);
}

.feature-icon {
    font-size: 2rem;
    margin-bottom: 0.5rem;
}

.feature-card h3 {
    margin-bottom: 0.4rem;
    font-size: 1.1rem;
}

.feature-card p {
    color: var(--color-text-muted);
    font-size: 0.92rem;
}

.content {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 3rem 1.5rem;
}

.content h1 {
    font-size: 2rem;
    margin-bottom: 2rem;
}

.content h2 {
    font-size: 1.4rem;
    margin: 2rem 0 1rem;
    color: var(--color-text);
}

.step-list {
    display: flex;
    flex-direction: column;
    gap: 1.2rem;
    margin-bottom: 2rem;
}

.step {
    display: flex;
    gap: 1rem;
    align-items: flex-start;
}

.step-number {
    background: var(--color-primary);
    color: #fff;
    width: 36px;
    height: 36px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    flex-shrink: 0;
}

.step-body h3 { margin-bottom: 0.25rem; }
.step-body p { color: var(--color-text-muted); font-size: 0.95rem; }

.info-box {
    background: var(--color-surface);
    border-left: 4px solid var(--color-primary);
    border-radius: var(--radius);
    padding: 1rem 1.2rem;
    margin-top: 2rem;
    color: var(--color-text-muted);
    font-size: 0.95rem;
}

.comparison-table {
    overflow-x: auto;
    margin-bottom: 2rem;
}

table {
    width: 100%;
    border-collapse: collapse;
    background: var(--color-surface);
    border-radius: var(--radius);
    overflow: hidden;
}

th, td {
    padding: 0.75rem 1rem;
    text-align: left;
    border-bottom: 1px solid var(--color-border);
}

th {
    background: var(--color-surface-hover);
    font-weight: 600;
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--color-text-muted);
}

.good { color: var(--color-good); }
.bad { color: var(--color-bad); }

.check-list, .cross-list {
    list-style: none;
    padding-left: 0;
    margin-bottom: 1.5rem;
}

.check-list li::before {
    content: "\2713 ";
    color: var(--color-good);
    font-weight: 700;
}

.cross-list li::before {
    content: "\2717 ";
    color: var(--color-bad);
    font-weight: 700;
}

.check-list li, .cross-list li {
    padding: 0.3rem 0;
    color: var(--color-text-muted);
}

.error-page {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 5rem 1.5rem;
    text-align: center;
}

.error-code {
    font-size: 6rem;
    font-weight: 800;
    color: var(--color-primary);
    line-height: 1;
    margin-bottom: 1rem;
}

.error-page h1 { margin-bottom: 0.5rem; }
.error-page p { color: var(--color-text-muted); margin-bottom: 1.5rem; }

.footer {
    text-align: center;
    padding: 2rem 1.5rem;
    border-top: 1px solid var(--color-border);
    color: var(--color-text-muted);
    font-size: 0.85rem;
}

.footer-note { margin-top: 0.3rem; }

@media (max-width: 768px) {
    .hero {
        flex-direction: column;
        padding: 2.5rem 1.5rem 2rem;
    }
    .hero h1 { font-size: 1.8rem; }
    .nav-links { gap: 1rem; }
    .navbar { padding: 0 1rem; }
}