I was using stripe with react and I was trying to use classes on parent container but it wasn't working for me. So, I ended up using inline styles for containers.Here is the final code that worked for me.
const containerStyles = {border: '1px solid #d3d3d3',padding: '5px 10px 5px 10px',borderRadius: '4px',width: '100%', };const cardNumberElementOptions = {style: { base: { fontSize: '14px', lineHeight: '45px', },},placeholder: 'Card Number',};<div style={containerStyles}><CardNumberElement options={cardNumberElementOptions} /></div>