Extend bootstrap row outside the container

One option is to use a CSS pseudo ::before element that will resize in height along with the col-lg-6..

#main {
    background: lightgreen;
    height: 100vh;
}

#main > .row {
    height: 100vh;
}

.left {
    background: red;
    position: relative;
    top: 50%;
    transform: translateY(-50%);
}

.left:before {
    left: -999em;
    background: red;
    content: '';
    display: block;
    position: absolute;
    width: 999em;
    top: 0;
    bottom: 0;
}
<div class="container" id="main">
    <div class="row">
        <div class="col-lg-6 left">
            ..
        </div>
    </div>
</div>

http://codeply.com/go/C80RYwhWrc

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Another option is to use an absolute position .container-fluid (full-width) behind the content .container that acts as a “ghost”…

.abs {
    position: absolute;
    right:0;
    top:0;
    bottom:0;
    z-index: 1;
}

<div class="container">
    <div class="row">
        <div class="col-sm-6">
            <h4>Content</h4>
        </div>
        <div class="col-sm-6">
            <!-- space over image -->
        </div>
    </div>
</div>
<div class="container-fluid abs">
    <div class="row h-100">
        <div class="col-sm-6 h-100">
            <!-- empty spacer -->
        </div>
        <div class="col-sm-6 right">
            <img src="//placehold.it/1000x400">
        </div>
    </div>
</div>

https://codeply.com/go/txUHH72f16 (Bootstrap 4)

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