The x-section-1 has an image as background:
<div id="cs-content" class="cs-content"><div id="x-section-1" class="x-section center-vertically bg-image parallax" style="margin: 0;padding: 0;min-height: 100vh; background-image: url(http://www.edinventa.com/wp-content/uploads/2017/07/background-heromask-videogame.jpg); background-color: hsl(49, 100%, 63%);" data-x-element="section" data-x-params="{"type":"image","parallax":true}" ><div class="x-container resp-p" style="margin: 0 auto 0px;padding: 0px 5%;width: 100%;max-width: 1110px;" >
In mobile, I want to show the following single color background instead: #3c3a35;
Could you tell me a simple way to achieve this? 
Thanks for your help… You are awesome!!! 
Carlos