HTML: в div с классом "extend-me" также добавьте класс "row" CSS: чтобы расширить внутренний div вправо, добавьте margin-left до 0 .extend-me {margin-left: 0;}
образец
<div class="container yourOverallContainer">
<div class="row">
<div class="col-sm-7">
<h1> Stack overflow question </h1>
</div>
</div>
</div>
<div class="container-fluid">
<div class="row">
<div class="col-sm-7 thisToBeAlignedToContainer">
<p>How can I get that div to extend to viewport right while maintaining its left edge to the Bootstrap column?</p>
</div>
<div class="col-sm-5">
<div class="extend-me row">
<img src="https://via.placeholder.com/350x150"/>
</div>
</div>
</div>
</div>
<div class="container">
<div class="row">
<footer>
<p id='feedback'> without jQuery and .container-fluid, yet completely responsive will be interesting... </p>
</footer>
</div>
</div>
.container {
background-color:#c9efb1;
}
.container-fluid {
background-color: #fff;
}
.extend-me {
background-color: darkred;
height: 300px;
}
.extend-me img {
object-fit: cover;
width: 100%;
height: 300px;
}
mWilson();
$(window).resize(function(){
mWilson();
});
function mWilson(){
$('.thisToBeAlignedToContainer').css('padding-left', $('.yourOverallContainer').css('margin-left'));
}