Our form looked like todoonada's also. We adjusted the CSS, per the Square installation instructions:

5. "The styling of the Square input fields is different from the rest of my payment input fields."
The module contains some CSS markup in the very bottom of the `/includes/modules/pages/checkout_payment/jscript_square.php` file, intended to create uniformity for the custom fields Square creates. For 99% of stores you will NOT need to change this; but in rare cases you may want to alter this CSS slightly to suit your needs.