change colors

I noticed that the navbar shortcode listing has no colors option. What's the reason for not providing info on how to change colors?

Specifically, I want to change the background color on a collapse (currently automatically blue):
<div class="container" style="z-index: 2;">
<div class="center collapsed subscribe-section-target" data-toggle="collapse" data-target="#target-1">
<h2 class="mb-0 mt-2 position-relative" style="z-index: 1;"><i class="icon-user-alt"></i>User Log Search
</h2>
</div>
<div class="collapse" id="target-1">
<div class="form-widget pb-5" data-alert-type="false">

I'm not trying to change the color of the navbar. In general, is there a way to change the background colors in different parts of the section? Is there a way to change the color of the Toggles, accordians and collapse functions? on this webpage, background color is only grey:
http://themes.semicolonweb.com/html/canvas/toggles-accordions.html

The background color relates to the code that is in the section:
<!-- Content
============================================= -->
<section id="content">
<div class="content-wrap py-0" style="overflow: visible">
<div class="bg-color subscribe-section position-relative" style="margin-top: 10px;">
<div class="container" style="z-index: 2;">
<div class="center collapsed subscribe-section-target" data-toggle="collapse" data-target="#target-1">
<h2 class="mb-0 mt-2 position-relative" style="z-index: 1;"><i class="icon-user-alt"></i>User Log Search
</h2>
</div>
<div class="collapse" id="target-1">
<div class="form-widget" data-alert-type="false">