:root {
  --bg: #f8fafc;
  --text: #0f172a;
  --muted: #64748b;
  --card: #ffffff;
  --border: #e2e8f0;
  --primary: #3b82f6;
  --primary-hover: #2563eb;
  --radius: 12px;
  --shadow: 0 4px 20px rgba(0, 0, 0, 0.06);
}

[data-theme="dark"] {
  --bg: #0f172a;
  --text: #f1f5f9;
  --muted: #94a3b8;
  --card: #1e293b;
  --border: #334155;
  --primary: #60a5fa;
  --primary-hover: #93c5fd;
  --shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  transition: background 0.3s, color 0.3s;
  min-height: 100vh;
}

.container {
  max-width: 720px;
  margin: 0 auto;
  padding: 0 20px 40px;
}

/* Header */
.header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 24px 0;
  border-bottom: 1px solid var(--border);
  margin-bottom: 48px;
}

.logo {
  font-size: 24px;
  font-weight: 700;
}

.nav {
  display: flex;
  gap: 24px;
}

.nav-link {
  color: var(--muted);
  text-decoration: none;
  font-size: 15px;
  transition: color 0.2s;
}

.nav-link:hover,
.nav-link.active {
  color: var(--text);
}

.theme-btn {
  background: none;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 6px 10px;
  cursor: pointer;
  font-size: 16px;
  transition: background 0.2s;
}

.theme-btn:hover {
  background: var(--card);
}

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

.title {
  font-size: 42px;
  font-weight: 700;
  letter-spacing: -0.5px;
  margin-bottom: 12px;
}

.subtitle {
  font-size: 20px;
  color: var(--muted);
  margin-bottom: 16px;
}

.desc {
  color: var(--muted);
  margin-bottom: 32px;
}

.actions {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
}

.btn {
  padding: 10px 20px;
  border-radius: 8px;
  border: none;
  font-size: 15px;
  cursor: pointer;
  transition: all 0.2s;
}

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

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

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

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

.status {
  margin-top: 20px;
  font-size: 14px;
  color: var(--muted);
  min-height: 20px;
}

/* Sections */
.section {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  margin-bottom: 24px;
  box-shadow: var(--shadow);
}

.section h2 {
  font-size: 22px;
  margin-bottom: 16px;
}

.section p {
  color: var(--muted);
  margin-bottom: 12px;
}

.feature-list {
  margin-top: 16px;
  padding-left: 20px;
  color: var(--muted);
}

.feature-list li {
  margin-bottom: 8px;
}

.contact-box {
  margin-top: 16px;
  padding: 16px;
  background: var(--bg);
  border-radius: 8px;
}

.contact-box a {
  color: var(--primary);
  text-decoration: none;
}

.contact-box a:hover {
  text-decoration: underline;
}

/* Footer */
.footer {
  text-align: center;
  padding: 32px 0 16px;
  color: var(--muted);
  font-size: 14px;
  border-top: 1px solid var(--border);
  margin-top: 40px;
}

/* Responsive */
@media (max-width: 600px) {
  .title {
    font-size: 32px;
  }

  .nav {
    gap: 16px;
  }

  .header {
    flex-wrap: wrap;
    gap: 12px;
  }
}