I am currently attempting to create the layout shown below for desktop using Bootstrap v4.3.
https://i.sstatic.net/HCm7z.jpg
This design should transition to the layout displayed below for mobile devices.
https://i.sstatic.net/4Kzad.jpg
However, upon running my code, I end up with the following outcome.
https://i.sstatic.net/sjmUZ.jpg
What could be the issue in the layout in my code?
<body>
<div class="container-fluid shop-page-main-container">
<div class="row">
<div class="col-xs-12 col-sm-12 col-md-3 col-lg-3 col-xl-3"style="border: 1px solid blue"><!-- Subnav container -->
<div class="row">
<div class="col-xs-6 col-sm-6 col-md-6 col-lg-12 col-xl-12" style="border: 1px solid red"><!-- Subnav content A -->
<div class="shop-page-subnav-box">
<h3 class="shop-page-subnav-box-header">
This is content A
</h3>
</div>
</div>
<div class="col-xs-6 col-sm-6 col-md-12 col-lg-12 col-xl-12" style="border: 1px solid green"><!-- Subnav content B -->
<div class="shop-page-subnav-box" style="margin-top: 10px">
<h3 class="shop-page-subnav-box-header">
This is content B
</h3>
</div>
</div>
</div>
</div>
<div class="col-xs-12 col-sm-12 col-md-9 col-lg-9 col-xl-9" style="border: 1px solid black"><!-- Main content -->
<div class="shop-page-breadcrumbs">
<h3 class="shop-page-subnav-box-header">
This is main content
</h3>
</span>
</div>
</div>
</div>
</body>