Bootstrap Carousel with Thumbnail Strip

Shows how to change the indicators in the Bootstrap carousel to be image based instead of the normal dots.

HTML

<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.5/js/bootstrap.min.js"></script>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.5/css/bootstrap.min.css">
<p>Below is an altered example that shows the indicators as thumbnails in a scrollable strip. This was accomplished with two markup changes and some CSS changes.</p>

<div id='carousel-custom' class='carousel slide' data-ride='carousel'>
        <!-- Wrapper for slides -->
        <div class='carousel-inner'>
            <div class='carousel-item active'>
                <img src='http://placehold.it/400x200&text=slide1' alt='' />
            </div>
            <div class='carousel-item'>
                <img src='http://placehold.it/400x200&text=slide2' alt='' />
            </div>
            <div class='carousel-item'>
                <img src='http://placehold.it/400x200&text=slide3' alt='' />
            </div>
                
            <div class='carousel-item'>
                <img src='http://placehold.it/400x200&text=slide4' alt='' />
            </div>
            <div class='carousel-item'>
                <img src='http://placehold.it/400x200&text=slide5' alt='' />
            </div>
            <div class='carousel-item'>
                <img src='http://placehold.it/400x200&text=slide6' alt='' />
            </div>
            
            <div class='carousel-item'>
                <img src='http://placehold.it/400x200&text=slide7' alt='' />
            </div>
            <div class='carousel-item'>
                <img src='http://placehold.it/400x200&text=slide8' alt='' />
            </div>
            <div class='carousel-item'>
                <img src='http://placehold.it/400x200&text=slide9' alt='' />
            </div>
            
            <!-- Controls -->
            <a class='left carousel-control' href='#carousel-custom' data-slide='prev'>
                <span class='glyphicon glyphicon-chevron-left'></span>
           ...

CSS

h4 {
    margin: 20px 10px 10px;
}
p {
    margin: 10px;
}

#carousel-example-generic {
    margin: 20px auto;
    width: 400px;
}

#carousel-custom {
    margin: 20px auto;
    width: 400px;
}
#carousel-custom .carousel-indicators {
    margin: 10px 0 0;
    overflow: auto;
    position: static;
    text-align: left;
    white-space: nowrap;
    width: 100%;
}
#carousel-custom .carousel-indicators li {
    background-color: transparent;
    -webkit-border-radius: 0;
    border-radius: 0;
    display: inline-block;
    height: auto;
    margin: 0 !important;
    width: auto;
}
#carousel-custom .carousel-indicators li img {
    display: block;
    opacity: 0.5;
}
#carousel-custom .carousel-indicators li.active img {
    opacity: 1;
}
#carousel-custom .carousel-indicators li:hover img {
    opacity: 0.75;
}