* { box-sizing: border-box; margin: 0; padding: 0; }
body { font-family: 'Segoe UI', Arial, sans-serif; line-height: 1.7; color: #1a1a2e; background: #f8f9fa; padding: 20px; }
.chapter { max-width: 860px; margin: 0 auto; background: #fff; padding: 40px; border-radius: 12px; box-shadow: 0 2px 12px rgba(0,0,0,.08); }
h1 { font-size: 2rem; color: #16213e; border-bottom: 3px solid #0f3460; padding-bottom: 10px; margin-bottom: 24px; }
h2 { font-size: 1.4rem; color: #0f3460; margin: 28px 0 12px; }
h3 { font-size: 1.1rem; color: #1a1a2e; margin: 20px 0 8px; }
p { margin-bottom: 14px; }
pre { background: #1a1a2e; color: #e4e4e4; padding: 16px; border-radius: 8px; overflow-x: auto; font-size: .9rem; margin: 12px 0; }
code { font-family: 'Fira Code', 'Consolas', monospace; }
pre code { background: none; padding: 0; }
img { max-width: 100%; height: auto; border-radius: 8px; margin: 16px 0; border: 1px solid #e0e0e0; }
nav { margin-top: 32px; padding-top: 20px; border-top: 1px solid #e0e0e0; display: flex; justify-content: space-between; flex-wrap: wrap; gap: 8px; }
nav a { color: #0f3460; text-decoration: none; font-weight: 600; padding: 8px 16px; border-radius: 6px; background: #eef2f7; transition: .2s; }
nav a:hover { background: #0f3460; color: #fff; }
.intro { margin-bottom: 14px; }
.why { margin-bottom: 14px; }
.story { background: #f8f9fa; border-left: 4px solid #0f3460; padding: 14px 18px; border-radius: 0 8px 8px 0; margin: 18px 0; font-style: italic; }
.steps { margin: 18px 0; }
.steps ol { padding-left: 22px; }
.steps li { margin-bottom: 6px; }
.reflection { background: #eef6ff; border-left: 4px solid #0f3460; padding: 14px 18px; border-radius: 0 8px 8px 0; margin: 18px 0; }
.closing { font-style: italic; text-align: center; margin-top: 28px; padding-top: 14px; border-top: 1px solid #e0e0e0; color: #555; }
.tag { display: inline-block; background: #0f3460; color: #fff; font-size: .75rem; padding: 2px 10px; border-radius: 12px; margin-bottom: 8px; }
@media (max-width: 600px) {
  body { padding: 10px; }
  .chapter { padding: 20px; }
  h1 { font-size: 1.5rem; }
  nav { flex-direction: column; align-items: stretch; }
  nav a { text-align: center; }
}