:root {
  --bg-color: #f4f4f4;
  --text-color: #333;
  --card-bg: #fff;
  --header-footer-bg: #333;
  --header-footer-text: #fff;
}

.dark-theme {
  --bg-color: #121212;
  --text-color: #eee;
  --card-bg: #1e1e1e;
  --header-footer-bg: #000;
  --header-footer-text: #fff;
}

body {
  margin: 0;
  font-family: 'Segoe UI', sans-serif;
  background-color: var(--bg-color);
  color: var(--text-color);
  transition: 0.3s ease-in-out;
}

header, footer {
  background: var(--header-footer-bg);
  color: var(--header-footer-text);
  padding: 20px;
  text-align: center;
}

#toggle-theme {
  margin-top: 10px;
  padding: 8px 16px;
  cursor: pointer;
  background: #0077cc;
  color: white;
  border: none;
  border-radius: 5px;
}

section {
  max-width: 900px;
  margin: auto;
  padding: 20px;
}

h2 {
  border-bottom: 2px solid var(--text-color);
  padding-bottom: 5px;
}

a {
  color: #0077cc;
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

.project-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  margin-top: 20px;
}

.project-card {
  background-color: var(--card-bg);
  padding: 15px;
  border-radius: 10px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

@media (max-width: 600px) {
  .project-grid {
    grid-template-columns: 1fr;
  }
}