Coming off Legacy Checkout – make inputs full width

I’m starting to look at moving clients off of the legacy checkout. On the new checkout there are divs around the inputs which set the widths at various breakpoints – GridCell p-GridCell–12 p-GridCell–xs6 p-GridCell–sm6 p-GridCell–md3.

I want all three input fields to be 100% wide on all breakpoints. I am able to do this with the legacy checkout. How can I achieve this with the new one? i have tried adding a rule for .p-GridCell, the one for .Input (from the docs) works but not the .p-GridCell one:

add_filter( 'wc_stripe_upe_params', function ( $stripe_params ) {

/**

* Custom shortcode checkout styles -- Use Stripe's Flat Theme

*/

$stripe_params['appearance'] = (object) [

'theme' => 'flat',

'variables' => (object) [

'colorPrimary' => '#0570de',

'colorBackground' => 'blue',

'colorText' => '#30313d', //label colour

'colorDanger' => '#df1b41',

'fontFamily' => 'futura-pt',

'spacingUnit' => '2px',

'borderRadius' => '4px',

],

'rules' => (object) [

'.p-GridCell' => (object) [

'width' => '100%'

],

'.Input' => (object) [

'color' => 'orange'

]

]

];

return $stripe_params;

} );