ctrlpanel/themes/default/sass/app.scss

// Fonts
@import url("https://fonts.googleapis.com/css?family=Source+Sans+Pro:300,400,400i,700&display=fallback");

// Bootstrap
@import "../css/stylesheet.css";
@import "../css/adminlte.min.css";
@import "../css/slim.min.css";

.checkout-gateways {
    // make the radio button clickable
    cursor: pointer;

    // add some space between all gateway divs bit the last one
    &:not(:last-child) {
        margin-bottom: 1rem;
    }
}

.checkout-gateway-label {
    // make the label clickable
    cursor: pointer;
    // center the label
    display: flex;
    justify-content: start;
    align-items: center;
}