:root {
  --bg: #ffffff;
  --text-primary: #111;
  --text-secondary: #666;
  --accent: #0071e3;
  --border: #eaeaea;
  --card-bg: #ffffff;
  --overlay-bg: rgba(255,255,255,0.75);
}

body.dark {
  --bg: #111;
  --text-primary: #fafafa;
  --text-secondary: #aaa;
  --accent: #79c0ff;
  --border: #333;
  --card-bg: #1a1a1a;
  --overlay-bg: rgba(0,0,0,0.75);
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text-primary);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.65;
  transition: background 0.3s ease, color 0.3s ease;
}

main {
  max-width: 780px;
  margin: 72px auto;
  padding: 0 28px;
}

h1 {
  font-family: Georgia, "Times New Roman", serif;
  font-size: 2.75rem;
  margin-bottom: 0.4rem;
  color: var(--text-primary);
}

.subtitle {
  color: var(--text-secondary);
  margin-bottom: 4rem;
}

section {
  margin-bottom: 4.5rem;
  padding-top: 2.2rem;
  border-top: 1px solid var(--border);
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.8s ease, transform 0.8s ease;
}

section:first-of-type {
  border-top: none;
  padding-top: 0;
}

section.visible {
  opacity: 1;
  transform: translateY(0);
}

h2 {
  font-size: 1.3rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 1rem;
}

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

li {
  margin-bottom: 1.4rem;
  color: var(--text-primary);
}

.muted {
  color: var(--text-secondary);
  font-size: 0.95rem;
}

a {
  color: var(--accent);
  text-decoration: none;
  font-weight: 500;
}

a:hover {
  text-decoration: underline;
}

.project-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  padding: 20px 22px;
  border-radius: 14px;
  cursor: pointer;
  transition: transform 0.25s ease, box-shadow 0.25s ease, background 0.3s ease, color 0.3s ease;
}

.project-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 12px 30px rgba(0,0,0,0.08);
}

.overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: var(--overlay-bg);
  backdrop-filter: blur(18px);
  align-items: center;
  justify-content: center;
  z-index: 999;
}

.flip-face {
  background: var(--card-bg);
  color: var(--text-primary);
  border-radius: 18px;
  padding: 28px;
  backface-visibility: hidden;
  box-shadow: 0 25px 60px rgba(0,0,0,0.15);
  transition: background 0.3s ease, color 0.3s ease;
}