Hi juankitacl
to change topnav background add this to your custom.css
.t3-topbar {
background:#yourcolor!important;
}
to change mainnav background add to the custom.css this code
.navbar-default {
background-color:#yourcolor!important;
}
If you do not have already a custom.css file than create a new one in this folder /templates/ja_platon/css/
Best regards
