:root {
    --bg: #08090f;
    --surface: #11131f;
    --surface-hover: #1a1d2e;
    --text: #e8eaf0;
    --text-muted: #8a8fa8;
    --accent: #6366f1;
    --accent-glow: rgba(99, 102, 241, 0.25);
    --border: rgba(255, 255, 255, 0.06);
    --radius: 16px;
    --shadow: 0 12px 40px rgba(0, 0, 0, 0.5);
    --ease: cubic-bezier(0.25, 0.8, 0.25, 1);
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: var(--bg);
    background-image: radial-gradient(circle at 50% 0%, #1a1d3a 0%, var(--bg) 70%);
    color: var(--text);
    line-height: 1.6;
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
}

.app {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 24px;
}

.chat-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 24px 0;
    border-bottom: 1px solid var(--border);
    margin-bottom: 40px;
}

.chat-header h1 {
    font-size: 1.5rem;
    font-weight: 700;
    letter-spacing: -0.02em;
}

.icon-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 44px;
    height: 44px;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 12px;
    font-size: 1.2rem;
    text-decoration: none;
    transition: all 0.2s var(--ease);
}

.icon-btn:hover {
    background: var(--surface-hover);
    border-color: var(--accent);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px var(--accent-glow);
}

.hero {
    text-align: center;
    padding: 40px 0 60px;
}

.hero h2 {
    font-size: clamp(2.2rem, 6vw, 3.5rem);
    font-weight: 800;
    line-height: 1.1;
    margin-bottom: 16px;
    background: linear-gradient(135deg, #ffffff 0%, #a5b4fc 50%, #6366f1 100%);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
}

.hero p {
    font-size: 1.25rem;
    color: var(--text-muted);
    max-width: 600px;
    margin: 0 auto;
}

.grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 24px;
    margin-bottom: 60px;
}

.card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 28px;
    transition: all 0.3s var(--ease);
    position: relative;
    overflow: hidden;
}

.card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--accent), #a78bfa);
    opacity: 0;
    transition: opacity 0.3s var(--ease);
}

.card:hover {
    transform: translateY(-6px);
    border-color: rgba(99, 102, 241, 0.4);
    box-shadow: var(--shadow);
}

.card:hover::before {
    opacity: 1;
}

.card h3 {
    font-size: 1.25rem;
    margin-bottom: 18px;
    display: flex;
    align-items: center;
    gap: 10px;
    color: var(--text);
}

.card ul {
    list-style: none;
}

.card li {
    padding: 10px 0;
    border-bottom: 1px solid var(--border);
    color: var(--text-muted);
    font-size: 0.95rem;
}

.card li:last-child {
    border-bottom: none;
}

.card li strong {
    color: var(--text);
    font-weight: 600;
}

.card code {
    background: var(--accent-soft);
    color: #818cf8;
    padding: 3px 8px;
    border-radius: 6px;
    font-family: 'Fira Code', 'Consolas', monospace;
    font-size: 0.85em;
    letter-spacing: 0.02em;
}

.footer {
    text-align: center;
    padding: 30px 0 50px;
    border-top: 1px solid var(--border);
    color: var(--text-muted);
    font-size: 0.95rem;
}

.hint {
    opacity: 0.7;
    margin-top: 8px;
}

@media (max-width: 768px) {
    .app { padding: 0 16px; }
    .hero { padding: 30px 0 40px; }
    .hero h2 { font-size: 2rem; }
    .grid { grid-template-columns: 1fr; gap: 16px; }
    .card { padding: 22px; }
}

.repo-link {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    margin-top: 24px;
    padding: 10px 20px;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 10px;
    color: var(--text);
    text-decoration: none;
    font-size: 0.95rem;
    font-weight: 500;
    transition: all 0.2s var(--ease);
}

.repo-link:hover {
    background: var(--surface-hover);
    border-color: var(--accent);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px var(--accent-glow);
}

.repo-link span {
    font-size: 1.1rem;
}