web-wallet: This way we are changing the main `dusk-card` style and not all cards needs to be of 100% width.

[kieranhall]

This way we are changing the main dusk-card style and not all cards needs to be of 100% width.
Not even all IconHeadingCards.

Maybe it's better to give the width on a per use basis.

Originally posted by @ascartabelli in https://github.com/dusk-network/dusk-pay-frontend/pull/45#discussion_r1963933845