html, body { height: 100%; }
body { font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial; line-height:1.5; color:#111; margin:0; display:flex; flex-direction:column; min-height:100vh }
/* Sticky header */
header { position: fixed; top:0; left:0; right:0; z-index:1000; padding: 1rem; background:#f7fafc; box-shadow: 0 1px 0 rgba(0,0,0,0.04) }
/* Add top padding to page content so it's not hidden under the fixed header */
.main-wrapper { padding-top: 120px; min-height: 95vh; box-sizing: border-box; flex:1 }
/* Footer placed after content; it will appear at end of content and at bottom of viewport when content is short */
footer { padding: 1rem; background:#f7fafc; box-shadow: 0 -1px 0 rgba(0,0,0,0.04) }
/* Ensure content has spacing and doesn't get hidden under footer */
.content { max-width: 900px; margin: 1.5rem auto; padding: 0 1rem 2rem; box-sizing: border-box }
nav a { margin-right: 0.6rem; color:#0366d6; text-decoration:none }
nav a.active { font-weight:600; text-decoration:underline }
pre { background:#f3f4f6; padding:0.75rem; border-radius:6px; overflow:auto }