To remove the border and make the background transparent, add the following CSS (cascading style sheets) code to the Survey Settings > Headers and Footers tab > HTML Head Tag section. In this case, the code modifies the predefined class style (acbc_byo_price_box) so that it removes the border and makes the background transparent.
<style type="text/css">
.acbc_byo_price_box {
border-style:none;
background-color:transparent;
}
</style>