:root {
  --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  
  /* Light Theme (Default) */
  --primary-color: #007bff;
  --text-color: #212529;
  --background-color: #fff;
  --header-bg: #f8f9fa;
  --card-bg: #f1f3f5;
  --border-color: #dee2e6;
  --hero-3d-opacity: 0.2;
}

[data-theme='dark'] {
  --primary-color: #4dabf7;
  --text-color: #f8f9fa;
  --background-color: #212529;
  --header-bg: #343a40;
  --card-bg: #495057;
  --border-color: #495057;
  --hero-3d-opacity: 0.1;
}

body {
  margin: 0;
  font-family: var(--font-family);
  background-color: var(--background-color);
  color: var(--text-color);
  line-height: 1.6;
  transition: background-color 0.2s ease, color 0.2s ease;
}

header {
  background-color: var(--header-bg);
  padding: 1rem;
  border-bottom: 1px solid var(--border-color);
}

.header-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
  max-width: 1200px;
  margin: 0 auto;
}

.logo {
  font-weight: bold;
  font-size: 1.2rem;
}

nav {
  display: flex;
  gap: 1.5rem;
}

:focus-visible {
  outline: 2px solid var(--primary-color);
  outline-offset: 2px;
  border-radius: 2px;
}

nav a {
  color: var(--primary-color);
  text-decoration: none;
  font-weight: 500;
}

nav a.active {
  text-decoration: underline;
}

main {
  padding: 2rem;
  max-width: 800px;
  margin: 0 auto;
}

.hero {
  position: relative;
  text-align: center;
  padding: 4rem 2rem;
  background-color: var(--header-bg);
  border-radius: 8px;
  overflow: hidden;
}

#hero-canvas {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 300px;
  height: 300px;
  opacity: var(--hero-3d-opacity);
  z-index: 0;
}

.hero h1, .hero p {
  position: relative;
  z-index: 1;
}

.hero h1 {
  font-size: 2.5rem;
  margin-bottom: 1rem;
}

#takeaways {
  text-align: center;
  padding: 2rem;
  background-color: var(--card-bg);
  border-radius: 8px;
  margin-top: 2rem;
}

h2 .material-symbols-outlined {
  vertical-align: middle;
  margin-right: 0.5rem;
}

footer {
  background-color: var(--header-bg);
  text-align: center;
  padding: 1rem;
  margin-top: 2rem;
  border-top: 1px solid var(--border-color);
}

@media (max-width: 600px) {
  nav {
    flex-direction: column;
    align-items: center;
  }
  .hero h1 {
    font-size: 2rem;
  }
}