Cannot bottom align image in jumbotron - twitter-bootstrap-3

Question

I'm trying to bottom align an img in a jumbotron, but cannot figure it out.
<div class="jumbotron">
<div class="container">
<div class="row">
<div class="col-lg-8">
<h1>Hello, world!</h1>
<p>This is a template for a simple marketing or informational website. It includes a large callout called the hero unit and three supporting pieces of content. Use it as a starting point to create something more unique.</p>
<p><a class="btn btn-primary btn-lg">Learn more »</a></p>
</div>
<div class="col-lg-4 text-center">
<img src="http://via.placeholder.com/200x200">
</div>
</div>
</div>
</div>
I tried adding the following to the CSS
.vertical-bottom {
display: flex;
align-items: bottom;
}
And then added the additional class to the DIV containing the img
<div class="col-lg-4 text-center vertical-bottom">
This didn't work, why is it so hard to vertically align things in bootstrap?

Answer 1

Here a kind of code:
Bootply
Css:
The media query is set to 1200 because I see you're using col-lg-xx
#media screen and (min-width:1200px) {
.flex_container img{
object-fit: contain;
object-position: 100% 100%;
}
.flex_container {
display: flex;
}
}
Html:
<div class="jumbotron">
<div class="container">
<div class="row flex_container">
<div class="col-lg-8">
<h1>Hello, world!</h1>
<p>This is a template for a simple marketing or informational website. It includes a large callout called the hero unit and three supporting pieces of content. Use it as a starting point to create something more unique.</p>
<p><a class="btn btn-primary btn-lg">Learn more »</a></p>
</div>
<div class="col-lg-4 text-center flex_container">
<img src="http://via.placeholder.com/200x200" style="">
</div>
</div>
</div>
</div>