body {
  font-family: 'Segoe UI', Arial, sans-serif;
  background: var(--bg, #fff);
  color: var(--text, #222);
  margin: 0;
}
header, footer { background: #1976d2; color: #fff; }
.navbar { display: flex; justify-content: space-between; align-items: center; padding: 1rem 2rem; }
.nav-links { display: flex; gap: 2rem; list-style: none; }
.nav-links a { color: #fff; text-decoration: none; font-weight: 500; }
#themeToggle { background: none; border: none; font-size: 1.2em; cursor: pointer; }
#mobileMenu { display: none; }
.sidebar { background: #f4f7fb; padding: 1em; margin-top: 1em; border-radius: 8px; }
.card { background: #fff; box-shadow: 0 2px 8px #0002; border-radius: 12px; margin-bottom: 2em; padding: 1em; }
.footer-content { text-align: center; padding: 1em 0; }
@media (max-width: 900px) {
  .nav-links { gap: 1rem; }
}
@media (max-width: 600px) {
  .nav-links { display: none; }
  #mobileMenu { display: inline; color: #fff; font-size: 2em; }
  .sidebar { display: none; }
}
[data-theme="dark"] {
  --bg: #181920;
  --text: #f0f0f0;
  background: var(--bg);
  color: var(--text);
}