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

:root {
  color-scheme: light;
  --bg:           #ffffff;
  --bg-surface:   #f5f5f7;
  --fg:           #1d1d1f;
  --fg-muted:     #6e6e73;
  --accent:       #0071e3;
  --accent-dim:   #0064cc;
  --accent-glow:  rgba(0, 113, 227, 0.10);
  --secondary:    #5856d6;
  --border:       #d2d2d7;
  --radius:       12px;
  --radius-sm:    6px;
  --font:         system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono:    ui-monospace, 'SF Mono', 'Cascadia Code', 'Fira Code', monospace;
}

html, body {
  background: var(--bg);
  color: var(--fg);
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Navigation */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  border-bottom: 1px solid var(--border);
  padding: 1rem 2rem;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  transition: padding 0.25s ease;
}

nav {
  max-width: 1100px;
  margin: 0 auto;
  width: 100%;
  display: flex;
  align-items: center;
  gap: 2rem;
}

.nav-brand {
  color: var(--accent);
  text-decoration: none;
  font-size: 1.1rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  transition: opacity 0.15s, font-size 0.25s ease;
}

.nav-brand:hover {
  opacity: 0.8;
}

.nav-link {
  color: var(--fg-muted);
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 500;
  transition: color 0.15s, font-size 0.25s ease;
}

.nav-link:hover {
  color: var(--fg);
}

.nav-link.active {
  color: var(--fg);
  border-bottom: 2px solid var(--accent);
  padding-bottom: 2px;
}

/* Compact header on mobile when scrolled */
@media (max-width: 768px) {
  .site-header.scrolled {
    padding-top: 0.4rem;
    padding-bottom: 0.4rem;
  }

  .site-header.scrolled .nav-brand {
    font-size: 0.9rem;
  }

  .site-header.scrolled .nav-link {
    font-size: 0.78rem;
  }
}

/* Main content */
main {
  flex: 1;
  max-width: 1100px;
  margin: 0 auto;
  padding: 3rem 2rem;
  width: 100%;
}

/* Footer */
footer {
  border-top: 1px solid var(--border);
  padding: 1.25rem 2rem;
  text-align: center;
  color: var(--fg-muted);
  font-size: 0.8rem;
}

/* Hero */
.hero {
  text-align: center;
  padding: 6rem 0 4rem;
}

.hero-badge {
  display: inline-block;
  background: var(--accent-glow);
  border: 1px solid rgba(0, 113, 227, 0.25);
  color: var(--accent);
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  padding: 0.35rem 1rem;
  border-radius: 999px;
  margin-bottom: 2rem;
}

.hero h1 {
  font-size: 3.5rem;
  font-weight: 800;
  letter-spacing: -0.04em;
  line-height: 1.1;
  margin-bottom: 1.25rem;
  background: linear-gradient(135deg, var(--fg) 30%, var(--accent) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero p {
  font-size: 1.2rem;
  color: var(--fg-muted);
  max-width: 520px;
  margin: 0 auto 2.5rem;
  line-height: 1.7;
}

/* Buttons */
.btn-primary {
  display: inline-block;
  background: var(--accent);
  color: #fff;
  text-decoration: none;
  font-size: 0.95rem;
  font-weight: 600;
  padding: 0.65rem 1.5rem;
  border-radius: var(--radius-sm);
  transition: background 0.15s, opacity 0.15s;
}

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

/* Typography */
h1 {
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 1rem;
}

h2 {
  font-size: 1.4rem;
  font-weight: 600;
  margin-bottom: 0.75rem;
}

p {
  color: var(--fg-muted);
  margin-bottom: 1rem;
}

a {
  color: var(--accent);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}