:root {
  --bg: #0f172a;
  --bg-top: #1e293b;
  --card: #111827;
  --text: #e5e7eb;
  --muted: #9ca3af;
  --accent: #3b82f6;
  --border: rgba(255, 255, 255, 0.08);
  --shadow: 0 20px 60px rgba(0, 0, 0, 0.5);
  --radius: 16px;
  --max-width: 900px;
}

* {
  box-sizing: border-box;
}

html {
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif;
  background: radial-gradient(circle at top, var(--bg-top), var(--bg));
  color: var(--text);
}

.container {
  max-width: var(--max-width);
  margin: auto;
  padding: 20px;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 20px 0;
  gap: 20px;
  flex-wrap: wrap;
}

.logo {
  font-weight: 600;
  letter-spacing: 2px;
}

nav {
  display: flex;
  flex-wrap: wrap;
}

nav a {
  margin-left: 20px;
  text-decoration: none;
  color: var(--muted);
  font-size: 14px;
}

nav a:first-child {
  margin-left: 0;
}

nav a:hover {
  color: #ffffff;
}

.card {
  background: var(--card);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
}

.hero-card {
  margin-top: 80px;
  padding: 60px 30px;
  text-align: center;
}

.content-card {
  padding: 40px;
}

h1 {
  margin-top: 0;
  margin-bottom: 15px;
  font-size: 48px;
  letter-spacing: -1px;
}

h2 {
  margin-top: 30px;
  font-size: 18px;
}

p,
li {
  line-height: 1.6;
}

.subtitle {
  color: var(--muted);
  font-size: 18px;
}

a {
  color: var(--accent);
}

footer {
  margin-top: 60px;
  text-align: center;
  font-size: 13px;
  color: var(--muted);
  padding-bottom: 20px;
}

@media (max-width: 640px) {
  .container {
    padding: 16px;
  }

  header {
    flex-direction: column;
    align-items: flex-start;
  }

  nav a {
    margin-left: 0;
    margin-right: 16px;
    margin-bottom: 8px;
  }

  h1 {
    font-size: 36px;
  }

  .hero-card {
    margin-top: 40px;
    padding: 40px 20px;
  }

  .content-card {
    padding: 24px;
  }
}