.popup { position: fixed; top: 0; left: 0; width: 100%; height: 100%; background: rgba(0, 0, 0, 0.7); display: flex; justify-content: center; align-items: center; } .popup-content { background: #fff; padding: 20px; border-radius: 8px; } .close { position: absolute; top: 10px; right: 10px; cursor: pointer; }<Modal ... style={{ overlay: { position: 'fixed', top: 0, left: 0, right: 0, bottom: 0, backgroundColor: 'rgba(255, 255, 255, 0.75)' }, content: { position: 'absolute', top: '40px', left: '40px', right: '40px', bottom: '40px', border: '1px solid #ccc', background: '#fff', overflow: 'auto', WebkitOverflowScrolling: 'touch', borderRadius: '4px', outline: 'none', padding: '20px' } }} ... >