/* General Styles */
:root {
  --primary-color: #3498db;
  --secondary-color: #2c3e50;
  --background-light: #f9f9f9;
  --background-dark: #1e1e1e;
  --text-light: #333;
  --text-dark: #f5f5f5;
  --card-bg-light: #fff;
  --card-bg-dark: #2c2c2c;
  --shadow-light: 0 8px 32px rgba(0, 0, 0, 0.1);
  --shadow-dark: 0 8px 32px rgba(255, 255, 255, 0.1);
}

body {
  font-family: 'Inter', sans-serif;
  line-height: 1.6;
  margin: 0;
  padding: 0;
  background-color: var(--background-light);
  color: var(--text-light);
  transition: background-color 0.3s ease, color 0.3s ease;
}

body.dark-mode {
  background-color: var(--background-dark);
  color: var(--text-dark);
}

.container {
  max-width: 800px;
  margin: 80px auto;
  padding: 40px;
  background-color: var(--card-bg-light);
  box-shadow: var(--shadow-light);
  border-radius: 16px;
  transition: background-color 0.3s ease, box-shadow 0.3s ease;
}

body.dark-mode .container {
  background-color: var(--card-bg-dark);
  box-shadow: var(--shadow-dark);
}

h1 {
  font-size: 2.5rem;
  color: var(--primary-color);
  margin-bottom: 20px;
  text-align: center;
  font-weight: 700;
}

h2 {
  font-size: 1.8rem;
  color: var(--secondary-color);
  margin-top: 30px;
  margin-bottom: 15px;
  font-weight: 600;
  position: relative;
}

body.dark-mode h2 {
  color: var(--primary-color);
}

h2::after {
  content: '';
  position: absolute;
  left: 0;
  bottom: -5px;
  width: 50px;
  height: 3px;
  background: linear-gradient(90deg, var(--primary-color), #9b59b6);
  border-radius: 2px;
}

p {
  font-size: 1.1rem;
  color: var(--text-light);
  margin-bottom: 20px;
}

body.dark-mode p {
  color: var(--text-dark);
}

a {
  color: var(--primary-color);
  text-decoration: none;
  transition: color 0.3s ease;
}

a:hover {
  color: #2980b9;
}

ul {
  margin: 15px 0;
  padding-left: 20px;
}

li {
  margin-bottom: 10px;
  font-size: 1rem;
  color: var(--text-light);
}

body.dark-mode li {
  color: var(--text-dark);
}

.footer {
  text-align: center;
  margin-top: 40px;
  font-size: 0.9rem;
  color: #777;
}

.footer a {
  color: #777;
}

.footer a:hover {
  color: #555;
}

/* Dark Mode Toggle */
.dark-mode-toggle {
  position: fixed;
  top: 20px;
  right: 20px;
  background: var(--primary-color);
  color: #fff;
  border: none;
  padding: 10px 15px;
  border-radius: 8px;
  cursor: pointer;
  font-size: 1rem;
  transition: background 0.3s ease;
}

.dark-mode-toggle:hover {
  background: #2980b9;
}

/* Sticky Header */
header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  background: var(--card-bg-light);
  box-shadow: var(--shadow-light);
  z-index: 1000;
  padding: 10px 0;
  text-align: center;
  transition: background 0.3s ease, box-shadow 0.3s ease;
}

body.dark-mode header {
  background: var(--card-bg-dark);
  box-shadow: var(--shadow-dark);
}

header h1 {
  font-size: 1.8rem;
  margin: 0;
}

/* Responsive Design */
@media (max-width: 768px) {
  .container {
    margin: 60px 20px;
    padding: 20px;
  }

  h1 {
    font-size: 2rem;
  }

  h2 {
    font-size: 1.5rem;
  }

  p {
    font-size: 1rem;
  }
}