html{
display:flex;
}
body{
min-height: 100vh;
width:100%;
display:flex;
flex-direction:column;
}
.header{
flex-shrink: 0;
}
.footer {
flex-shrink: 0;
background: #000000;
}
.content{
flex-grow:1;
}
<link href="https://stackpath.bootstrapcdn.com/bootstrap/4.5.0/css/bootstrap.min.css" rel="stylesheet"/>
<div class="header">
<nav class="navbar navbar-expand-lg navbar-light bg-light">
<a class="navbar-brand" href="#">Navbar</a>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNav" aria-controls="navbarNav" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarNav">
<ul class="navbar-nav">
<li class="nav-item active">
<a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Features</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Pricing</a>
</li>
<li class="nav-item">
<a class="nav-link disabled" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
</li>
</ul>
</div>
</nav>
</div>
<div class="content">
<div class="ml-5 mr-5 mb-3">
<!--Carousel-->
<div id="carouselExampleIndicators" class="carousel slide" data-ride="carousel">
<ol class="carousel-indicators">
<li data-target="#carouselExampleIndicators" data-slide-to="0" class="active"></li>
<li data-target="#carouselExampleIndicators" data-slide-to="1"></li>
<li data-target="#carouselExampleIndicators" data-slide-to="2"></li>
</ol>
<div class="carousel-inner">
<div class="carousel-item active">
<img class="d-block w-100" src="https://cp12.nevsepic.com.ua/2-1/1358115669-1037168-www.nevsepic.com.ua.jpg" alt="First slide">
</div>
<div class="carousel-item">
<img class="d-block w-100" src="https://cp12.nevsepic.com.ua/2-1/1358115669-1037168-www.nevsepic.com.ua.jpg" alt="Second slide">
</div>
<div class="carousel-item">
<img class="d-block w-100" src="https://cp12.nevsepic.com.ua/2-1/1358115669-1037168-www.nevsepic.com.ua.jpg" alt="Third slide">
</div>
</div>
<a class="carousel-control-prev" href="#carouselExampleIndicators" role="button" data-slide="prev">
<span class="carousel-control-prev-icon" aria-hidden="true"></span>
<span class="sr-only">Previous</span>
</a>
<a class="carousel-control-next" href="#carouselExampleIndicators" role="button" data-slide="next">
<span class="carousel-control-next-icon" aria-hidden="true"></span>
<span class="sr-only">Next</span>
</a>
</div>
<!--Cards-->
<div class="card-deck">
<div class="card">
<img src="https://lh3.googleusercontent.com/proxy/VrXfgT75SzZSdv4_fUbujEBcWspapF079o24SolSQXCa2SS6ZV5TGxosjjj5DUJEco351bmm1HfHdMo7c3P9vTTP2ZUO0bVlxs4s9SeVKu7OavwktBNL" class="card-img-top" alt="...">
<div class="card-body">
<h5 class="card-title">Card title</h5>
<p class="card-text">This is a longer card with supporting text below as a natural lead-in to additional content. This content is a little bit longer.</p>
<p class="card-text"><small class="text-muted">Last updated 3 mins ago</small></p>
</div>
</div>
<div class="card">
<img src="https://lh3.googleusercontent.com/proxy/VrXfgT75SzZSdv4_fUbujEBcWspapF079o24SolSQXCa2SS6ZV5TGxosjjj5DUJEco351bmm1HfHdMo7c3P9vTTP2ZUO0bVlxs4s9SeVKu7OavwktBNL" class="card-img-top" alt="...">
<div class="card-body">
<h5 class="card-title">Card title</h5>
<p class="card-text">This card has supporting text below as a natural lead-in to additional content.</p>
<p class="card-text"><small class="text-muted">Last updated 3 mins ago</small></p>
</div>
</div>
<div class="card">
<img src="https://lh3.googleusercontent.com/proxy/VrXfgT75SzZSdv4_fUbujEBcWspapF079o24SolSQXCa2SS6ZV5TGxosjjj5DUJEco351bmm1HfHdMo7c3P9vTTP2ZUO0bVlxs4s9SeVKu7OavwktBNL" class="card-img-top" alt="...">
<div class="card-body">
<h5 class="card-title">Card title</h5>
<p class="card-text">This is a wider card with supporting text below as a natural lead-in to additional content. This card has even longer content than the first to show that equal height action.</p>
<p class="card-text"><small class="text-muted">Last updated 3 mins ago</small></p>
</div>
</div>
</div>
</div>
</div>
<div class="footer">
<div class="container">
<div class="row text-center justify-content-center pt-3">
<div class="col-md-3 mb-3">
<h6>
<a class="text-smr" href="#">Ohter Sites:</a>
</h6>
</div>
<div class="col-md-2 mb-3">
<h6 class="font-weight-bold">
<a class="link-f" href="#">Site 1</a>
</h6>
</div>
<div class="col-md-2 mb-3">
<h6>
<a class="link-f" href="#">Site 2</a>
</h6>
</div>
<div class="col-md-2 mb-3">
<h6>
<a class="link-f" href="#">Site 3</a>
</h6>
</div>
<div class="col-md-2 mb-3">
<h6>
<a class="link-f" href="#">Site 4</a>
</h6>
</div>
</div>
</div>
<script src="https://code.jquery.com/jquery-3.5.1.slim.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/popper.js@1.16.0/dist/umd/popper.min.js"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.5.0/js/bootstrap.min.js"></script>