/* General Styles */
body {
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
  line-height: 1.6;
  background-color: #f0f8ff; /* Light blue background */
  color: #333;
}
h1, h2, h3, h4 {
  margin-top: 1em;
  margin-bottom: 0.5em;
}
h1 {
  font-size: 2em;
  margin-bottom: 0.2em;
  color: #006699;
}
h2 {
  font-size: 1.5em;
  border-bottom: 2px solid #006699;
  padding-bottom: 0.2em;
  color: #006699;
}
h3 {
  font-size: 1.2em;
  margin-top: 1.5em;
  color: #004466;
}
h4 {
  font-size: 1.1em;
  font-style: italic;
  margin-top: 1em;
  color: #005577;
}
p, ul, li {
  font-size: 0.95em;
}
ul {
  margin: 0.5em 0 1em 1.2em;
}
li {
  margin-bottom: 0.5em;
}

/* Navigation Bar */
nav {
  position: fixed;
  top: 0;
  width: 100%;
  background-color: #007acc; /* Lighter blue nav */
  opacity: 0.95;
  padding: 0.5em 0;
  z-index: 1000;
  box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}
nav ul {
  list-style: none;
  text-align: center;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 1em;
}
nav li {
  display: inline;
}
nav a {
  color: #fff;
  text-decoration: none;
  font-weight: bold;
  padding: 0.5em;
  display: inline-block;
}
nav a:hover {
  text-decoration: underline;
}

/* Sections and Layout */
header {
  text-align: center;
  padding: 6em 1em 2em;
  background: #e6f2ff; /* Light blue header */
}
header h1 {
  font-size: 2.5em;
  color: #004466;
}
header h2 {
  font-size: 1.3em;
  font-weight: normal;
  color: #555;
}
section {
  padding: 2em 1em;
  max-width: 800px;
  margin: 0 auto;
  background-color: #ffffff;
  border-radius: 8px;
  box-shadow: 0 2px 4px rgba(0,0,0,0.05);
  margin-bottom: 2em;
}
#portfolio h3 {
  margin-top: 1em;
  color: #2c3e50;
}
#portfolio h4 {
  margin-top: 0.8em;
  color: #34495e;
}
footer {
  text-align: center;
  padding: 1em;
  font-size: 0.9em;
  color: #666;
  background-color: #e6f2ff;
  border-top: 1px solid #ccc;
}

/* Responsive Design */
@media (max-width: 600px) {
  nav ul {
    flex-direction: column;
    gap: 0.5em;
  }
  nav li {
    display: block;
    margin: 0;
  }
  header {
    padding: 4em 1em 1.5em;
  }
  section {
    padding: 1.5em 1em;
  }
}

/* Image (Diagram) Styling */
section#portfolio img {
  display: block;
  max-width: 100%;
  height: auto;
  margin: 1em auto;
  border: 1px solid #ccc;
  border-radius: 4px;
}