Controlling height of pre container in bootstrap - html

Question

I have an app using Bootstrap 5.0 laid out as in the dashboard example. In the main content column, I have a heading followed by a set of tabs. Each tab contains a block of preformatted text in a pre tag. The preformatted text can be both wide and tall, so scroll bars are needed in both directions. I have set up a codepen to demonstrate the issue.
By default, the pre element is the full height of the content and the vertical scroll bar is attached to the page instead of the pre element. This means that in order to access the hortizontal scroll bar, users have to scroll the page down to the very bottom so they lose track of what they were looking at when they needed to scroll horizontally.
What I really want is to limit the height of the pre block to the vertical space available on the page so that both the vertical and horizontal scroll bars are attached to the pre element itself. I have managed to almost achieve what I want by setting the max-height of the pre as follows:
.scrollable-pre {
max-height: calc(100vh - 16em);
}
However, this is brittle because if add anything to the heading that increases its height, the hard coded 16em will have to be adjusted.
How do I get the pre to automatically size to the available height?
body {
font-size: .875rem;
}
.feather {
width: 16px;
height: 16px;
vertical-align: text-bottom;
}
/*
* Sidebar
*/
.sidebar {
position: fixed;
top: 0;
/* rtl:raw:
right: 0;
*/
bottom: 0;
/* rtl:remove */
left: 0;
z-index: 100;
/* Behind the navbar */
padding: 48px 0 0;
/* Height of navbar */
box-shadow: inset -1px 0 0 rgba(0, 0, 0, .1);
}
#media (max-width: 767.98px) {
.sidebar {
top: 5rem;
}
}
.sidebar-sticky {
position: relative;
top: 0;
height: calc(100vh - 48px);
padding-top: .5rem;
overflow-x: hidden;
overflow-y: auto;
/* Scrollable contents if viewport is shorter than content. */
}
.sidebar .nav-link {
font-weight: 500;
color: #333;
}
.sidebar .nav-link .feather {
margin-right: 4px;
color: #727272;
}
.sidebar .nav-link.active {
color: #2470dc;
}
.sidebar .nav-link:hover .feather,
.sidebar .nav-link.active .feather {
color: inherit;
}
.sidebar-heading {
font-size: .75rem;
text-transform: uppercase;
}
/*
* Navbar
*/
.navbar-brand {
padding-top: .75rem;
padding-bottom: .75rem;
font-size: 1rem;
background-color: rgba(0, 0, 0, .25);
box-shadow: inset -1px 0 0 rgba(0, 0, 0, .25);
}
.navbar .navbar-toggler {
top: .25rem;
right: 1rem;
}
.navbar .form-control {
padding: .75rem 1rem;
border-width: 0;
border-radius: 0;
}
.form-control-dark {
color: #fff;
background-color: rgba(255, 255, 255, .1);
border-color: rgba(255, 255, 255, .1);
}
.form-control-dark:focus {
border-color: transparent;
box-shadow: 0 0 0 3px rgba(255, 255, 255, .25);
}
.pre-container {}
.scrollable-pre {
max-height: calc(100vh - 16em);
}
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap#5.1.3/dist/css/bootstrap.min.css" integrity="sha384-1BmE4kWBq78iYhFldvKuhfTAU6auU8tT94WrHftjDbrCEXSU1oBoqyl2QvZ6jIW3" crossorigin="anonymous">
<header class="navbar navbar-dark sticky-top bg-dark flex-md-nowrap p-0 shadow">
<a class="navbar-brand col-md-3 col-lg-2 me-0 px-3" href="#">Company name</a>
<button class="navbar-toggler position-absolute d-md-none collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#sidebarMenu" aria-controls="sidebarMenu" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<input class="form-control form-control-dark w-100" type="text" placeholder="Search" aria-label="Search">
<div class="navbar-nav">
<div class="nav-item text-nowrap">
<a class="nav-link px-3" href="#">Sign out</a>
</div>
</div>
</header>
<div class="container-fluid">
<div class="row">
<nav id="sidebarMenu" class="col-md-3 col-lg-2 d-md-block bg-light sidebar collapse">
<div class="position-sticky pt-3">
<ul class="nav flex-column">
<li class="nav-item">
<a class="nav-link active" aria-current="page" href="#">
<span data-feather="home"></span> Dashboard
</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">
<span data-feather="file"></span> Orders
</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">
<span data-feather="shopping-cart"></span> Products
</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">
<span data-feather="users"></span> Customers
</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">
<span data-feather="bar-chart-2"></span> Reports
</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">
<span data-feather="layers"></span> Integrations
</a>
</li>
</ul>
<h6 class="sidebar-heading d-flex justify-content-between align-items-center px-3 mt-4 mb-1 text-muted">
<span>Saved reports</span>
<a class="link-secondary" href="#" aria-label="Add a new report">
<span data-feather="plus-circle"></span>
</a>
</h6>
<ul class="nav flex-column mb-2">
<li class="nav-item">
<a class="nav-link" href="#">
<span data-feather="file-text"></span> Current month
</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">
<span data-feather="file-text"></span> Last quarter
</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">
<span data-feather="file-text"></span> Social engagement
</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">
<span data-feather="file-text"></span> Year-end sale
</a>
</li>
</ul>
</div>
</nav>
<main class="col-md-9 ms-sm-auto col-lg-10 px-md-4">
<div class="d-flex justify-content-between flex-wrap flex-md-nowrap align-items-center pt-3 pb-2 mb-3 border-bottom">
<h1 class="h2">Dashboard</h1>
<div class="btn-toolbar mb-2 mb-md-0">
<div class="btn-group me-2">
<button type="button" class="btn btn-sm btn-outline-secondary">Share</button>
<button type="button" class="btn btn-sm btn-outline-secondary">Export</button>
</div>
<button type="button" class="btn btn-sm btn-outline-secondary dropdown-toggle">
<span data-feather="calendar"></span>
This week
</button>
</div>
</div>
<ul class="nav nav-tabs" id="myTab" role="tablist">
<li class="nav-item" role="presentation">
<button class="nav-link active" id="home-tab" data-bs-toggle="tab" data-bs-target="#home" type="button" role="tab" aria-controls="home" aria-selected="true">Home</button>
</li>
<li class="nav-item" role="presentation">
<button class="nav-link" id="profile-tab" data-bs-toggle="tab" data-bs-target="#profile" type="button" role="tab" aria-controls="profile" aria-selected="false">Profile</button>
</li>
<li class="nav-item" role="presentation">
<button class="nav-link" id="contact-tab" data-bs-toggle="tab" data-bs-target="#contact" type="button" role="tab" aria-controls="contact" aria-selected="false">Contact</button>
</li>
</ul>
<div class="tab-content" id="myTabContent">
<div class="tab-pane fade show active" id="home" role="tabpanel" aria-labelledby="home-tab">
<div class="pre-container">
<pre class="scrollable-pre">
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
</pre>
</div>
</div>
<div class="tab-pane fade" id="profile" role="tabpanel" aria-labelledby="profile-tab">...</div>
<div class="tab-pane fade" id="contact" role="tabpanel" aria-labelledby="contact-tab">...</div>
</div>
</main>
</div>
</div>
<script src="https://cdn.jsdelivr.net/npm/bootstrap#5.1.3/dist/js/bootstrap.bundle.min.js" integrity="sha384-ka7Sk0Gln4gmtz2MlQnikT1wXgYsOg+OMhuP+IlRH9sENBO0LRn5q+8nbTov4+1p" crossorigin="anonymous"></script>