*{box-sizing:border-box}html,body{color:#111827;background:#f4f4f5;min-height:100%;margin:0;font-family:Arial,Helvetica,sans-serif}.app-shell{justify-content:center;align-items:center;min-height:100vh;padding:24px;display:flex}.card{background:#fff;border:1px solid #e5e7eb;border-radius:10px;flex-direction:column;gap:12px;width:100%;max-width:420px;padding:24px;display:flex}h1,p{margin:0}button{cursor:pointer;background:#fff;border:1px solid #d1d5db;border-radius:8px;padding:10px 14px;font-size:14px}button:hover{background:#f9fafb}button:disabled{cursor:not-allowed;opacity:.7}.error-text{color:#b91c1c}