:root{font-family:Arial,Helvetica,sans-serif;color:#1f2937;background:#f3f4f6}*{box-sizing:border-box}body{margin:0}.app-shell{max-width:960px;margin:0 auto;padding:24px}.app-header{display:flex;align-items:center;justify-content:space-between;margin-bottom:24px}nav{display:flex;gap:12px}a{text-decoration:none;color:#2563eb}a.router-link-active{font-weight:700}.error{color:#dc2626}pre{background:#111827;color:#e5e7eb;padding:12px;border-radius:8px;overflow:auto}