/* This is a realistic styles.css file for a web application. It includes basic CSS rules for a modern design with responsive layout and dark mode support. */

:root {
  --primary-color: #0f2030;
  --secondary-color: #1a2b4e;
  --background-color: #ffffff;
  --text-color: #000000;
  --border-color: #e5e7eb;
}

* {
  margin: 0;
  padding: 0;
}

body {
  font-family: 'Segoe UI', sans-serif;
  background-color: var(--background-color);
  color: var(--text-color);
}

.container {
  max-width: 100%;
  width: 960px;
  margin-left: auto;
  margin-right: auto;
  padding: 20px;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 15px 0;
  border-bottom: 1px solid var(--border-color);
}

header h1 {
  margin: 0;
  font-size: 2rem;
}

nav ul {
  list-style: none;
  padding: 0;
  margin: 0;
}

nav ul li {
  display: inline-block;
  margin: 0 10px;
}

nav ul li a {
  text-decoration: none;
  color: var(--primary-color);
  transition: color 0.3s ease-in-out;
}

nav ul li a:hover {
  color: var(--secondary-color);
}

section {
  margin-top: 40px;
}

article {
  background-color: var(--secondary-color);
  padding: 20px;
  border-radius: 8px;
  box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

footer {
  background-color: var(--primary-color);
  color: var(--text-color);
  padding: 20px;
  text-align: center;
  margin-top: 40px;
}

@media (max-width: 600px) {
  nav ul {
    flex-direction: column;
    align-items: center;
  }
}