:root {
  --primary-color: #2a7d2e;
  --secondary-color: #4a9e4e;
  --accent-color: #8cc63f;
  --text-color: #333;
  --bg-color: #fff;
  --nav-bg: #f5f5f5;
  --footer-bg: #333;
  --footer-text: #f5f5f5;
}

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

body {
  font-family: 'Open Sans', sans-serif;
  line-height: 1.6;
  color: var(--text-color);
  background-color: var(--bg-color);
}

h1, h2, h3, h4, h5, h6 {
  font-family: 'Merriweather', serif;
  margin-bottom: 1rem;
  color: var(--primary-color);
}

h1 {
  font-size: 2.5rem;
}

h2 {
  font-size: 2rem;
}

h3 {
  font-size: 1.5rem;
}

p {
  margin-bottom: 1.5rem;
  font-size: 1.1rem;
}

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

a:hover {
  text-decoration: underline;
}

.container {
  width: 80%;
  max-width: 1200px;
  margin: 0 auto;
}

header {
  background-image: linear-gradient(rgba(0, 0, 0, 0.5), rgba(0, 0, 0, 0.5)), url("../images/800px-Mobile_Bay_and_Delta_from_space.jpg");
  color: white;
  padding: 6rem 0;
  text-align: center;
}

header h1 {
  color: white;
  font-size: 3rem;
  margin-bottom: 1rem;
}

header h2 {
  color: var(--accent-color);
  font-size: 1.5rem;
  font-weight: 300;
  margin-bottom: 1.5rem;
}

.author {
  font-style: italic;
  font-size: 1.2rem;
}

nav {
  background-color: var(--nav-bg);
  padding: 1rem 0;
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
  position: sticky;
  top: 0;
  z-index: 100;
}

nav ul {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  list-style: none;
}

nav ul li {
  margin: 0 0.5rem;
}

nav ul li a {
  display: block;
  padding: 0.5rem 1rem;
  color: var(--primary-color);
  font-weight: 600;
  border-radius: 4px;
  transition: 0.3s;
}

nav ul li a:hover {
  background-color: var(--primary-color);
  color: white;
  text-decoration: none;
}

main {
  padding: 3rem 0;
}

section {
  margin-bottom: 4rem;
  padding-top: 1rem;
}

section h2 {
  border-bottom: 2px solid var(--secondary-color);
  padding-bottom: 0.5rem;
  margin-bottom: 1.5rem;
}

.references {
  list-style-type: none;
  padding-left: 0;
}

.references li {
  margin-bottom: 1rem;
  padding-left: 1.5rem;
  position: relative;
}

.references li::before {
  content: "•";
  position: absolute;
  left: 0;
  color: var(--secondary-color);
}

footer {
  background-color: var(--footer-bg);
  color: var(--footer-text);
  padding: 2rem 0;
  text-align: center;
}

footer p {
  margin-bottom: 0.5rem;
}

@media (max-width: 768px) {
  header {
    padding: 4rem 0;
  }
  
  header h1 {
    font-size: 2.2rem;
  }
  
  header h2 {
    font-size: 1.2rem;
  }
  
  nav ul {
    flex-direction: column;
    align-items: center;
  }
  
  nav ul li {
    margin: 0.25rem 0;
    width: 100%;
    text-align: center;
  }
  
  h1 {
    font-size: 2rem;
  }
  
  h2 {
    font-size: 1.5rem;
  }
  
  p {
    font-size: 1rem;
  }
}

@media (max-width: 480px) {
  .container {
    width: 95%;
    padding: 0 10px;
  }
  
  header {
    padding: 3rem 0;
  }
  
  header h1 {
    font-size: 1.8rem;
  }
  
  header h2 {
    font-size: 1rem;
  }
}

@media print {
  nav, footer {
    display: none;
  }
  
  body {
    font-size: 12pt;
    line-height: 1.5;
  }
  
  a {
    color: black;
    text-decoration: none;
  }
  
  h1, h2, h3, h4, h5, h6 {
    break-after: avoid;
    break-inside: avoid;
  }
  
  p, li {
    break-inside: avoid;
  }
  
  header {
    background: none;
    color: black;
    padding: 1rem 0;
  }
  
  header h1, header h2 {
    color: black;
  }
}