/* Reset */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

/* Color variables */
:root {
  --nav-text-color: #fff;
  --nav-active-color: #bb86fc;
  --bg-color: #121212;
  --text-color: #e0e0e0;
}
[data-theme="light"] {
  --nav-text-color: #333;
  --nav-active-color: #589cc9;
  --bg-color: #f0f0f0;
  --text-color: #333;
}

body {
  background: var(--bg-color);
  color: var(--text-color);
  font-family: Arial, sans-serif;
  line-height: 1.6;
}

/* Header and sticky nav */
header .header-content {
  padding: 2rem 1rem;
  text-align: center;
}
.sticky-nav {
  position: sticky;
  top: 0;
  width: 100%;
  background: transparent;
  padding: 0.75rem 1rem;
  display: flex;
  justify-content: center;
  align-items: center;
  z-index: 1000;
}

.sticky-nav ul {
  display: flex;
  gap: 1.5rem;
  list-style: none;
}

.sticky-nav a.nav-link {
  position: relative;
  color: var(--nav-text-color);
  text-decoration: none;
  font-size: 1rem;
  font-weight: 500;
  transition: color 0.3s;
}
.sticky-nav a.nav-link:hover,
.sticky-nav a.nav-link.active {
  color: var(--nav-active-color);
}
.sticky-nav a.nav-link.active::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 100%;
  height: 2px;
  background: var(--nav-active-color);
}

/* Section anchor offset */
main {
  scroll-margin-top: 60px;
}

/* Responsive images */
img {
  max-width: 100%;
  height: auto;
}

/* Dark/light toggle */
#mode-toggle {
  margin-left: 2rem;
  background: none;
  border: none;
  color: var(--nav-active-color);
  font-size: 1rem;
  cursor: pointer;
}