*{box-sizing:border-box}html,body{color:#0f172a;background:#f8fafc;margin:0;padding:0;font-family:Inter,-apple-system,BlinkMacSystemFont,Segoe UI,sans-serif}.app-shell{place-items:center;min-height:100vh;padding:24px;display:grid}.shell-card{background:#fff;border:1px solid #e2e8f0;border-radius:12px;width:100%;max-width:720px;padding:24px}.shell-title{margin:0 0 8px;font-size:28px;font-weight:600;line-height:1.2}.shell-subtitle{color:#475569;margin:0;font-size:16px;line-height:1.5}