dipendrapancholi

Use below CSS for this:

@media only screen and (max-width: 480px) {

.content-area .edd_price_options ul {
border: 1px solid #f2f2f2;
border-radius: 4px;
text-align: center;
}

.content-area .edd_download_purchase_form .edd_price_options li {
padding: 8px 15px;
margin-bottom: 0;
border-bottom: 1px solid #f2f2f2;
}
.content-area .edd_download_purchase_form .edd-submit {
width: 100%;
}

}

Yes, You can sell ebboks in PDF format using this plugin. Also there are many extension available for the plugin. You can install Strip payment gateway.
Here is the link: https://easydigitaldownloads.com/downloads/stripe-gateway/