:root{color-scheme:light;font-family:Segoe UI,Tahoma,Geneva,Verdana,sans-serif;line-height:1.5;font-weight:400;color:#0f172a;background:#f8fafc}*{box-sizing:border-box}body{margin:0}a{color:#0f766e}.app-shell{max-width:920px;margin:0 auto;padding:2rem 1rem}header{display:flex;justify-content:space-between;align-items:center;gap:1rem;margin-bottom:2rem}.nav-links{display:flex;gap:.8rem}.nav-links a{text-decoration:none;padding:.4rem .6rem;border-radius:.35rem}.nav-links a.active{background:#ccfbf1;color:#134e4a}main{background:#fff;border:1px solid #e2e8f0;border-radius:.75rem;padding:1.2rem}