:root {
  --bg: #ffffff;
  --fg: #0b1220;
  --muted: #4b5563;
  --brand: #0369a1;
  --brand-2: #0284c7;
  --surface: #f1f5f9;
  --radius: 8px;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

* {
  box-sizing: border-box;
}

html:focus-within {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  line-height: 1.6;
}

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

a:hover {
  text-decoration: underline;
}

:focus {
  outline: 2px solid var(--brand);
  outline-offset: 2px;
}

.container {
  max-width: 1200px;
  margin-inline: auto;
  padding: 1rem;
}

header {
  position: sticky;
  top: 0;
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: saturate(180%) blur(8px);
  border-bottom: 1px solid #e5e7eb;
  z-index: 20;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 700;
}

nav ul {
  display: flex;
  gap: 0.75rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-link {
  padding: 0.5rem 0.75rem;
  border-radius: 8px;
}

.nav-link:focus,
.nav-link:hover {
  background: var(--surface);
}

.menu-btn {
  display: none;
  background: none;
  border: 1px solid #e5e7eb;
  padding: 0.5rem 0.75rem;
  border-radius: 8px;
}

@media (max-width: 760px) {
  nav ul {
    display: none;
  }
  
  nav[aria-expanded="true"] ul {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    padding: 0.5rem 0;
  }
  
  .menu-btn {
    display: inline-block;
  }
}

main {
  display: block;
}

footer {
  padding: 2rem 1rem;
  border-top: 1px solid #e5e7eb;
  background: #fff;
  text-align: center;
}


.skip-link {
  position: absolute;
  left: -9999px;
  top: auto;
  width: 1px;
  height: 1px;
  overflow: hidden;
}

.skip-link:focus {
  position: static;
  width: auto;
  height: auto;
  padding: 0.5rem;
  border: 1px dashed var(--brand);
  background: #fff;
}


/* Responsive design */
@media (max-width: 768px) {
  .hero {
    flex-direction: column;
    text-align: center;
  }
  
  .hero h1 {
    font-size: 2rem;
  }
  
  .container {
    padding: 0.5rem;
  }
}