Hello,
The Message Seller button is not visible enough.
I suggest taking the blue style :
class="btn btn-es-primary btn-block btn-lg"
And to encourage guest visitors to contact the advertiser, this Message Seller button should always be visible.
If the user is not logged in, the login popup would be displayed
The mechanism would be the same as currently for Guests who click for example on a Like button of a publication. The popup login is displayed automatically.
Thank you,
Philippe