:root {
  color-scheme: dark;
  --bg: #040816;
  --surface: rgba(10, 16, 34, 0.88);
  --surface-strong: rgba(13, 20, 42, 0.96);
  --text: #f7fbff;
  --muted: #90a4c9;
  --accent: #6ee7ff;
  --accent-secondary: #7c3aed;
  --border: rgba(255,255,255,0.12);
  --shadow: 0 24px 50px rgba(2, 8, 23, 0.35);
}

body[data-theme="light"] {
  color-scheme: light;
  --bg: #f5f8ff;
  --surface: rgba(255,255,255,0.92);
  --surface-strong: rgba(255,255,255,0.98);
  --text: #0f172a;
  --muted: #475569;
  --accent: #2563eb;
  --accent-secondary: #8b5cf6;
  --border: rgba(15, 23, 42, 0.12);
  --shadow: 0 20px 42px rgba(15, 23, 42, 0.12);
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; font-family: Inter, system-ui, -apple-system, sans-serif; background: var(--bg); color: var(--text); }
body { min-height: 100vh; }
a { color: inherit; text-decoration: none; }
button, input, textarea { font: inherit; }
.app-shell { max-width: 1300px; margin: 0 auto; padding: 20px; }
.topbar { display:flex; align-items:center; justify-content:space-between; padding: 14px 18px; border-radius: 999px; background: var(--surface); border: 1px solid var(--border); box-shadow: var(--shadow); backdrop-filter: blur(16px); }
.brand { display:flex; align-items:center; gap: 10px; font-weight: 700; }
.brand-mark { width: 42px; height: 42px; border-radius: 14px; display:grid; place-items:center; background: linear-gradient(135deg, var(--accent), var(--accent-secondary)); color:white; }
.brand small { display:block; color: var(--muted); font-size: .72rem; }
.nav-links { display:flex; align-items:center; gap: 14px; }
.nav-links a, .theme-toggle, .icon-btn { color: var(--text); background: transparent; border: none; cursor: pointer; }
.theme-toggle, .icon-btn { border-radius: 999px; padding: 8px 10px; background: rgba(255,255,255,0.05); }
.hero-grid { display:grid; grid-template-columns: 1.1fr 0.9fr; gap: 24px; align-items:center; min-height: 80vh; }
.hero-copy h1 { font-size: clamp(2rem, 4vw, 3.4rem); line-height: 1.04; margin: 10px 0; }
.eyebrow { text-transform: uppercase; letter-spacing: .3em; color: var(--accent); font-size: .8rem; font-weight: 700; }
.hero-text { color: var(--muted); font-size: 1.05rem; line-height: 1.8; max-width: 600px; }
.hero-actions { display:flex; gap: 12px; flex-wrap: wrap; margin-top: 24px; }
.btn { display:inline-flex; align-items:center; justify-content:center; border: 1px solid transparent; border-radius: 999px; padding: 11px 16px; cursor: pointer; transition: transform .2s ease; }
.btn:hover { transform: translateY(-1px); }
.btn-primary { background: linear-gradient(135deg, var(--accent), var(--accent-secondary)); color:white; }
.btn-secondary { background: rgba(255,255,255,0.06); color: var(--text); border-color: var(--border); }
.hero-stats { display:flex; flex-wrap: wrap; gap: 12px; margin-top: 24px; }
.stat-card, .hero-card, .card, .sidebar-card, .chat-card, .auth-card { background: var(--surface); border: 1px solid var(--border); border-radius: 24px; box-shadow: var(--shadow); }
.stat-card { padding: 12px 14px; color: var(--muted); }
.hero-card { padding: 20px; }
.demo-chat { display:grid; gap: 12px; }
.bubble { padding: 12px 14px; border-radius: 16px; line-height: 1.6; max-width: 90%; }
.bubble.ai { background: rgba(255,255,255,0.06); }
.bubble.user { margin-left: auto; background: linear-gradient(135deg, rgba(110,231,255,0.24), rgba(124,58,237,0.24)); }
.chat-layout { display:grid; grid-template-columns: 280px 1fr; gap: 20px; margin-top: 18px; }
.sidebar-card, .chat-card, .card, .auth-card { padding: 18px; }
.messages { min-height: 420px; max-height: 560px; overflow-y:auto; padding: 8px 0; display:grid; gap: 12px; }
.message-row { display:flex; gap: 8px; align-items:flex-end; }
.message-row.user { justify-content:flex-end; }
.message-bubble { max-width: 92%; padding: 12px 14px; border-radius: 16px; background: rgba(255,255,255,0.06); line-height: 1.7; white-space: pre-wrap; }
.message-row.user .message-bubble { background: linear-gradient(135deg, rgba(110,231,255,0.24), rgba(124,58,237,0.24)); }
.message-meta { display:flex; gap: 8px; margin-top: 8px; font-size: 0.8rem; color: var(--muted); }
.message-actions button { border:none; background: transparent; color: var(--accent); cursor: pointer; padding: 0 4px; }
.composer { display:grid; gap: 12px; margin-top: 12px; }
textarea { border-radius: 16px; padding: 12px 14px; border: 1px solid var(--border); background: rgba(255,255,255,0.04); color: var(--text); min-height: 110px; resize: vertical; }
.composer-actions { display:flex; justify-content:space-between; gap: 10px; }
.full-width { width: 100%; }
.toast { position: fixed; right: 20px; bottom: 20px; background: rgba(4,8,22,0.95); color:white; padding: 12px 16px; border-radius: 999px; opacity:0; transform: translateY(12px); pointer-events:none; transition: all .25s ease; z-index: 30; }
.toast.show { opacity:1; transform: translateY(0); }
.auth-page { min-height: 100vh; display:grid; place-items:center; padding: 20px; }
.auth-card { width: min(100%, 420px); display:grid; gap: 12px; }
.auth-card label { display:grid; gap: 6px; color: var(--muted); }
.auth-card input { border-radius: 14px; border: 1px solid var(--border); background: rgba(255,255,255,0.05); color: var(--text); padding: 10px 12px; }
.link-btn { color: var(--accent); text-align: center; }
.page-content { display:grid; gap: 18px; margin-top: 20px; }
.conversation-item { padding: 10px 0; border-bottom: 1px solid var(--border); cursor:pointer; color: var(--muted); }
.conversation-item:last-child { border-bottom: none; }
pre { background: rgba(0,0,0,0.24); padding: 12px; border-radius: 12px; overflow:auto; }
code { font-family: Consolas, monospace; }
table { width:100%; border-collapse: collapse; margin-top: 8px; }
th, td { border: 1px solid var(--border); padding: 8px; text-align:left; }
@media (max-width: 900px) { .hero-grid, .chat-layout { grid-template-columns: 1fr; } .sidebar-card { order: 2; } }
@media (max-width: 640px) { .app-shell { padding: 14px; } .topbar { border-radius: 20px; flex-wrap: wrap; gap: 10px; } .nav-links { width:100%; justify-content:flex-end; } .composer-actions { flex-direction: column; } }