Utility API
Utilities are single-purpose classes that you combine directly in markup. Stack several on one element, add a breakpoint infix such as d-md-flex to change behaviour from a screen size up, and tune colour states through CSS variables like --ui-bg-opacity, --ui-border-opacity and --ui-link-opacity. The recipes below build complete interface pieces without writing any custom CSS.
1A card made only of utilities
Background, border, radius, padding and shadow utilities stacked on a plain div give you a card without the card component.
Keynote
Be in the room where it happens
Virtual passes let you join the main stage live from anywhere.
<div class="bg-page border rounded-lg p-4 shadow-sm" style="max-width:22rem">
<p class="small text-muted uppercase font-semibold mb-1">Keynote</p>
<h3 class="h5 mb-2">Be in the room where it happens</h3>
<p class="mb-0 text-muted">Virtual passes let you join the main stage live from anywhere.</p>
</div>2Responsive display: d-none d-md-flex
Breakpoint infixes switch a utility on from a screen size up. Resize the window: the toolbar row appears from md, the compact button below it.
d-none d-md-flex and d-flex d-md-none
<div class="border rounded-lg p-4 bg-surface-3">
<div class="hidden md:flex gap-2">
<button type="button" class="btn btn-sm btn-primary"><i class="bi bi-pencil-square" aria-hidden="true"></i> Edit</button>
<button type="button" class="btn btn-sm btn-outline-secondary"><i class="bi bi-share-fill" aria-hidden="true"></i> Share</button>
<button type="button" class="btn btn-sm btn-outline-danger"><i class="bi bi-trash3-fill" aria-hidden="true"></i> Delete</button>
</div>
<div class="flex md:hidden">
<button type="button" class="btn btn-sm btn-primary w-full"><i class="bi bi-three-dots" aria-hidden="true"></i> Actions</button>
</div>
<p class="small text-muted mt-2 mb-0"><code>d-none d-md-flex</code> and <code>d-flex d-md-none</code></p>
</div>3State via --ui-bg-opacity
Every bg-{colour} reads the --ui-bg-opacity variable, so one inline variable fades the fill (the labels sit under it, so they stay readable on every step).
<div class="flex flex-wrap gap-4 small text-center">
<div>
<div class="bg-primary rounded-md mb-1" style="width:3.5rem;height:2.5rem;--ui-bg-opacity:1">
</div>
1
</div>
<div>
<div class="bg-primary rounded-md mb-1" style="width:3.5rem;height:2.5rem;--ui-bg-opacity:.6">
</div>
.6
</div>
<div>
<div class="bg-primary rounded-md mb-1" style="width:3.5rem;height:2.5rem;--ui-bg-opacity:.35">
</div>
.35
</div>
<div>
<div class="bg-primary rounded-md mb-1" style="width:3.5rem;height:2.5rem;--ui-bg-opacity:.15">
</div>
.15
</div>
<div>
<div class="bg-primary rounded-md mb-1 border" style="width:3.5rem;height:2.5rem;--ui-bg-opacity:.05">
</div>
.05
</div>
</div>4State via --ui-border-opacity
Border colour utilities read --ui-border-opacity; set it inline for values between the border-opacity-* steps.
<div class="row g-2">
<div class="col-6 col-md-3">
<div class="border border-2 border-success rounded-lg p-4 text-center small" style="--ui-border-opacity:1">
1
</div>
</div>
<div class="col-6 col-md-3">
<div class="border border-2 border-success rounded-lg p-4 text-center small" style="--ui-border-opacity:.6">
.6
</div>
</div>
<div class="col-6 col-md-3">
<div class="border border-2 border-success rounded-lg p-4 text-center small" style="--ui-border-opacity:.3">
.3
</div>
</div>
<div class="col-6 col-md-3">
<div class="border border-2 border-success rounded-lg p-4 text-center small" style="--ui-border-opacity:.1">
.1
</div>
</div>
</div>5State via --ui-link-opacity
Coloured links read --ui-link-opacity: fade a link that is not available yet, or fade on hover - a link people must read stays at full strength.
- Sponsorship --ui-link-opacity:.5, not available
- Networking lounges 100, 75 on hover
- Join the conference of the year link-danger, faint underline
<ul class="list-unstyled mb-0 grid gap-2">
<li><a href="#" class="link-primary pointer-events-none" style="--ui-link-opacity:.5" aria-disabled="true" tabindex="-1">Sponsorship</a> <span class="small text-muted">--ui-link-opacity:.5, not available</span></li>
<li><a href="#" class="link-primary link-opacity-100 link-opacity-75-hover">Networking lounges</a> <span class="small text-muted">100, 75 on hover</span></li>
<li><a href="#" class="link-danger link-underline-opacity-25">Join the conference of the year</a> <span class="small text-muted">link-danger, faint underline</span></li>
</ul>6Media object
d-flex with gap, flex-shrink-0 on the image and flex-grow-1 on the text is the classic comment or list row.
Every attendee receives a certificate of participation.
<div class="flex gap-4 items-start border rounded-lg p-4">
<img src="../assets/img/avatar-9.svg" alt="Maya Larsen" width="48" height="48" class="rounded-full shrink-0">
<div class="grow">
<div class="flex justify-between">
<strong>Maya Larsen</strong><small class="text-muted">just now</small>
</div>
<p class="mb-0 small">Every attendee receives a certificate of participation.</p>
</div>
</div>7Status badges without the badge component
Subtle backgrounds, emphasis text, small padding and rounded-pill compose a soft status label.
<div class="flex flex-wrap gap-2">
<span class="inline-flex items-center gap-1 px-2 py-1 rounded-full small font-medium bg-success-subtle text-success-emphasis border border-success/30"><i class="bi bi-check-circle-fill" aria-hidden="true"></i> Active</span> <span class="inline-flex items-center gap-1 px-2 py-1 rounded-full small font-medium bg-warning-subtle text-warning-emphasis border border-warning/30"><i class="bi bi-clock-fill" aria-hidden="true"></i> Pending</span> <span class="inline-flex items-center gap-1 px-2 py-1 rounded-full small font-medium bg-danger-subtle text-danger-emphasis border border-danger/30"><i class="bi bi-x-circle-fill" aria-hidden="true"></i> Blocked</span>
</div>8Stat tile
Font size, weight, line height and colour utilities turn three lines of text into a dashboard metric.
<div class="row g-3">
<div class="col-sm-6 col-lg-4">
<div class="p-4 rounded-xl bg-surface-3 border">
<div class="flex justify-between items-center mb-2">
<span class="small text-muted font-medium">Revenue</span><span class="text-primary-ink text-lg"><i class="bi bi-graph-up-arrow" aria-hidden="true"></i></span>
</div>
<div class="text-2xl font-bold leading-none">
$28,922.95
</div>
<div class="small text-success-emphasis mt-1">
<i class="bi bi-arrow-up" aria-hidden="true"></i> +31% this month
</div>
</div>
</div>
<div class="col-sm-6 col-lg-4">
<div class="p-4 rounded-xl bg-surface-3 border">
<div class="flex justify-between items-center mb-2">
<span class="small text-muted font-medium">Customers</span><span class="text-info-emphasis text-lg"><i class="bi bi-people-fill" aria-hidden="true"></i></span>
</div>
<div class="text-2xl font-bold leading-none">
6.8k
</div>
<div class="small text-danger-emphasis mt-1">
<i class="bi bi-arrow-down" aria-hidden="true"></i> -7% this month
</div>
</div>
</div>
</div>9Avatar with a status dot
position-relative on the wrapper, then position-absolute, bottom-0 / end-0 and a white border for the online dot.
Online
Away
<div class="flex gap-6 items-center">
<div class="relative inline-block">
<img src="../assets/img/avatar-3.svg" alt="Nadia Sato" width="56" height="56" class="rounded-full"> <span class="absolute bottom-0 end-0 p-2 bg-success border border-2 border-white rounded-full"><span class="sr-only">Online</span></span>
</div>
<div class="relative inline-block">
<img src="../assets/img/avatar-11.svg" alt="Jonah Mensah" width="56" height="56" class="rounded-full"> <span class="absolute bottom-0 end-0 p-2 bg-secondary border border-2 border-white rounded-full"><span class="sr-only">Away</span></span>
</div>
</div>10Responsive alignment
text-center on phones and text-md-start from md: a hero block that centres only where it should.
Three days that change how you work
Every detail is handled by people who care about getting it right.
Get started<div class="p-6 rounded-xl bg-primary-subtle text-center md:text-start">
<h3 class="h4 font-bold text-primary-emphasis">Three days that change how you work</h3>
<p class="mb-4 text-primary-emphasis">Every detail is handled by people who care about getting it right.</p>
<a href="#" class="btn btn-primary">Get started</a>
</div>11Stack on phones, row on tablets
flex-column flex-md-row with gap-3: three blocks stack on small screens and line up from md.
<div class="flex flex-col md:flex-row gap-4">
<div class="flex-auto p-4 rounded-lg border bg-surface-3">
<i class="bi bi-lightning-charge-fill" aria-hidden="true"></i> <strong>Mobile agenda</strong>
</div>
<div class="flex-auto p-4 rounded-lg border bg-surface-3">
<i class="bi bi-shield-check" aria-hidden="true"></i> <strong>Networking lounges</strong>
</div>
<div class="flex-auto p-4 rounded-lg border bg-surface-3">
<i class="bi bi-cloud-arrow-up-fill" aria-hidden="true"></i> <strong>Mobile agenda</strong>
</div>
</div>12Callout from border-start
A single side border with a thick width and a theme colour makes a note or warning callout.
Every attendee receives a certificate of participation.
<div class="border-s border-4 border-warning bg-warning-subtle rounded-end-3 p-4">
<div class="font-semibold text-warning-emphasis mb-1">
<i class="bi bi-exclamation-triangle-fill" aria-hidden="true"></i> Heads up
</div>
<p class="mb-0 small text-warning-emphasis">Every attendee receives a certificate of participation.</p>
</div>13Settings row
justify-content-between and align-items-center place a label on the left and a control on the right.
<div class="border rounded-lg">
<div class="flex justify-between items-center p-4 border-b">
<div>
<div class="font-medium">
Email alerts
</div>
<div class="small text-muted">
Daily summary at 13:00
</div>
</div>
<span class="px-2 py-1 rounded-full small bg-success text-white">On</span>
</div>
<div class="flex justify-between items-center p-4">
<div>
<div class="font-medium">
Push notifications
</div>
<div class="small text-muted">
Only mentions
</div>
</div>
<span class="px-2 py-1 rounded-full small bg-surface-2 text-muted">Off</span>
</div>
</div>14Announcement bar
text-bg-dark sets a contrasting text colour with the background; small and gap utilities do the rest.
<div class="text-bg-dark rounded-lg px-4 py-2 flex flex-wrap items-center justify-center gap-2 small">
<span class="badge text-bg-warning">New</span> <span>Big ideas, small rooms, real conversations</span> <a href="#" class="link-light link-offset-2 font-semibold">Read more</a>
</div>15Filter chips that wrap
flex-wrap with gap-2 lets a row of chips flow onto new lines without margin hacks.
<div class="flex flex-wrap gap-2">
<span class="px-4 py-1 rounded-full text-bg-primary small">All</span> <span class="px-4 py-1 rounded-full border small">update</span> <span class="px-4 py-1 rounded-full border small">Meetup</span> <span class="px-4 py-1 rounded-full border small">secure</span> <span class="px-4 py-1 rounded-full border small">idea</span>
</div>16Product line item
A thumbnail, a truncated title and a right-aligned price: overflow-hidden on the middle column lets text-truncate work in flex.
<div class="flex items-center gap-4 border rounded-lg p-2" style="max-width:28rem">
<img src="../assets/img/product-7.svg" alt="Evening meetup" width="56" height="56" class="rounded-md object-cover shrink-0">
<div class="grow overflow-hidden">
<div class="font-medium truncate">
Evening meetup - reliable edition
</div>
<div class="small text-muted">
Meetup
</div>
</div>
<div class="font-bold whitespace-nowrap">
$26.00
</div>
</div>17Responsive spacing
p-2 p-md-4 and mb-2 mb-md-3: tighter padding on phones, roomier from md, no media query needed.
How to pitch a talk that gets accepted
Every session is recorded, so you can catch up on anything you missed. Clear prices, honest advice and no surprises along the way.
<div class="border rounded-xl p-2 md:p-6 bg-surface-3">
<h3 class="h6 mb-2 md:mb-4">How to pitch a talk that gets accepted</h3>
<p class="mb-0 small">Every session is recorded, so you can catch up on anything you missed. Clear prices, honest advice and no surprises along the way.</p>
</div>18Underline that appears on hover
link-underline-opacity-0 hides the underline, the -hover variants bring it back with a little offset.
<nav class="flex flex-wrap gap-4" aria-label="Footer">
<a href="#" class="link-body-emphasis link-offset-2 link-underline-opacity-0 link-underline-opacity-100-hover">About</a> <a href="#" class="link-body-emphasis link-offset-2 link-underline-opacity-0 link-underline-opacity-100-hover">Pricing</a> <a href="#" class="link-body-emphasis link-offset-2 link-underline-opacity-0 link-underline-opacity-100-hover">Support</a> <a href="#" class="link-body-emphasis link-offset-2 link-underline-opacity-0 link-underline-opacity-100-hover">Careers</a>
</nav>19Image with a text overlay
position-relative wrapper, an absolutely placed caption at bottom-0 and bg-dark with --ui-bg-opacity for the scrim.
<div class="relative rounded-xl overflow-hidden" style="max-width:26rem">
<img src="https://images.unsplash.com/photo-1560439514-0fc9d2cd5e1b?auto=format&fit=crop&w=1200&h=800&q=70" alt="Learn, connect and get inspired" class="w-full block">
<div class="absolute bottom-0 start-0 end-0 bg-dark text-white p-4" style="--ui-bg-opacity:.6">
<div class="small text-white/50">
Seoul
</div>
<div class="font-semibold">
Meet the people shaping the future
</div>
</div>
</div>20Empty state panel
A centred flex column with a large icon, muted text and one action, built from spacing and text utilities.
No files yet
Thousands of attendees already trust us, and we work hard to keep it that way.
<div class="flex flex-col items-center text-center py-12 px-4 border rounded-xl bg-surface-3">
<div class="text-4xl text-tertiary mb-2">
<i class="bi bi-folder2-open" aria-hidden="true"></i>
</div>
<h3 class="h6 font-semibold mb-1">No files yet</h3>
<p class="small text-muted mb-4">Thousands of attendees already trust us, and we work hard to keep it that way.</p>
<button type="button" class="btn btn-sm btn-primary"><i class="bi bi-cloud-arrow-up-fill" aria-hidden="true"></i> Upload</button>
</div>