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.

Mountain

Trips designed around you

The new free cancellation gives your work organised all year round.

<div class="bg-body border rounded-3 p-3 shadow-sm" style="max-width:22rem">
  <p class="small text-body-secondary text-uppercase fw-semibold mb-1">Mountain</p>
  <h3 class="h5 mb-2">Trips designed around you</h3>
  <p class="mb-0 text-body-secondary">The new free cancellation gives your work organised all year round.</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-3 p-3 bg-body-tertiary">
  <div class="d-none d-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="d-flex d-md-none">
    <button type="button" class="btn btn-sm btn-primary w-100"><i class="bi bi-three-dots" aria-hidden="true"></i> Actions</button>
  </div>
  <p class="small text-body-secondary 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 while the text stays fully opaque.

.35

.15

.05

<div class="d-flex flex-wrap gap-2">
  <div class="bg-primary text-white rounded-2 px-3 py-2" style="--ui-bg-opacity:1">
    1
  </div>
  <div class="bg-primary rounded-2 px-3 py-2" style="--ui-bg-opacity:.6">
    .6
  </div>
  <div class="bg-primary rounded-2 px-3 py-2" style="--ui-bg-opacity:.35">
    .35
  </div>
  <div class="bg-primary rounded-2 px-3 py-2" style="--ui-bg-opacity:.15">
    .15
  </div>
  <div class="bg-primary rounded-2 px-3 py-2" style="--ui-bg-opacity:.05">
    .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-3 p-3 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-3 p-3 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-3 p-3 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-3 p-3 text-center small" style="--ui-border-opacity:.1">
      .1
    </div>
  </div>
</div>

5State via --ui-link-opacity

Coloured links read --ui-link-opacity. Combine it with the -hover utilities for a link that brightens on hover.

Car rental --ui-link-opacity:.5
Flexible dates 50, 100 on hover
Explore more, worry less link-opacity-75

<ul class="list-unstyled mb-0 d-grid gap-2">
  <li><a href="#" class="link-primary" style="--ui-link-opacity:.5">Car rental</a> <span class="small text-body-secondary">--ui-link-opacity:.5</span></li>
  <li><a href="#" class="link-primary link-opacity-50 link-opacity-100-hover">Flexible dates</a> <span class="small text-body-secondary">50, 100 on hover</span></li>
  <li><a href="#" class="link-danger link-opacity-75">Explore more, worry less</a> <span class="small text-body-secondary">link-opacity-75</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.

Samir Delgadoyesterday

The new flexible dates makes customers coming back wherever you are.

<div class="d-flex gap-3 align-items-start border rounded-3 p-3">
  <img src="../assets/img/avatar-10.svg" alt="Samir Delgado" width="48" height="48" class="rounded-circle flex-shrink-0"> 
  <div class="flex-grow-1">
    <div class="d-flex justify-content-between">
      <strong>Samir Delgado</strong><small class="text-body-secondary">yesterday</small>
    </div>
    <p class="mb-0 small">The new flexible dates makes customers coming back wherever you are.</p>
  </div>
</div>

7Status badges without the badge component

Subtle backgrounds, emphasis text, small padding and rounded-pill compose a soft status label.

Active Pending Blocked

<div class="d-flex flex-wrap gap-2">
  <span class="d-inline-flex align-items-center gap-1 px-2 py-1 rounded-pill small fw-medium bg-success-subtle text-success-emphasis border border-success-subtle"><i class="bi bi-check-circle-fill" aria-hidden="true"></i> Active</span> <span class="d-inline-flex align-items-center gap-1 px-2 py-1 rounded-pill small fw-medium bg-warning-subtle text-warning-emphasis border border-warning-subtle"><i class="bi bi-clock-fill" aria-hidden="true"></i> Pending</span> <span class="d-inline-flex align-items-center gap-1 px-2 py-1 rounded-pill small fw-medium bg-danger-subtle text-danger-emphasis border border-danger-subtle"><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.

Revenue

$41,151.41

+65% this month

Customers

8.3k

-5% this month

<div class="row g-3">
  <div class="col-sm-6 col-lg-4">
    <div class="p-3 rounded-4 bg-body-tertiary border">
      <div class="d-flex justify-content-between align-items-center mb-2">
        <span class="small text-body-secondary fw-medium">Revenue</span><span class="text-primary fs-5"><i class="bi bi-graph-up-arrow" aria-hidden="true"></i></span>
      </div>
      <div class="fs-3 fw-bold lh-1">
        $41,151.41
      </div>
      <div class="small text-success mt-1">
        <i class="bi bi-arrow-up" aria-hidden="true"></i> +65% this month
      </div>
    </div>
  </div>
  <div class="col-sm-6 col-lg-4">
    <div class="p-3 rounded-4 bg-body-tertiary border">
      <div class="d-flex justify-content-between align-items-center mb-2">
        <span class="small text-body-secondary fw-medium">Customers</span><span class="text-info fs-5"><i class="bi bi-people-fill" aria-hidden="true"></i></span>
      </div>
      <div class="fs-3 fw-bold lh-1">
        8.3k
      </div>
      <div class="small text-danger mt-1">
        <i class="bi bi-arrow-down" aria-hidden="true"></i> -5% 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.

<div class="d-flex gap-4 align-items-center">
  <div class="position-relative d-inline-block">
    <img src="../assets/img/avatar-9.svg" alt="Kenji Silva" width="56" height="56" class="rounded-circle"> <span class="position-absolute bottom-0 end-0 p-2 bg-success border border-2 border-white rounded-circle"><span class="visually-hidden">Online</span></span> 
  </div>
  <div class="position-relative d-inline-block">
    <img src="../assets/img/avatar-7.svg" alt="Ruby Varga" width="56" height="56" class="rounded-circle"> <span class="position-absolute bottom-0 end-0 p-2 bg-secondary border border-2 border-white rounded-circle"><span class="visually-hidden">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.

Trips designed around you

A elegant team lets customers coming back with friendly support.

Get started

<div class="p-4 rounded-4 bg-primary-subtle text-center text-md-start">
  <h3 class="h4 fw-bold text-primary-emphasis">Trips designed around you</h3>
  <p class="mb-3 text-primary-emphasis">A elegant team lets customers coming back with friendly support.</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.

Best price guarantee

24/7 assistance

Free cancellation

<div class="d-flex flex-column flex-md-row gap-3">
  <div class="flex-fill p-3 rounded-3 border bg-body-tertiary">
    <i class="bi bi-lightning-charge-fill" aria-hidden="true"></i> <strong>Best price guarantee</strong>
  </div>
  <div class="flex-fill p-3 rounded-3 border bg-body-tertiary">
    <i class="bi bi-shield-check" aria-hidden="true"></i> <strong>24/7 assistance</strong>
  </div>
  <div class="flex-fill p-3 rounded-3 border bg-body-tertiary">
    <i class="bi bi-cloud-arrow-up-fill" aria-hidden="true"></i> <strong>Free cancellation</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.

Heads up

This friendly plan helps projects moving forward at a fair price.

<div class="border-start border-4 border-warning bg-warning-subtle rounded-end-3 p-3">
  <div class="fw-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">This friendly plan helps projects moving forward at a fair price.</p>
</div>

13Settings row

justify-content-between and align-items-center place a label on the left and a control on the right.

Email alerts

Daily summary at 19:30

Push notifications

Only mentions

Off

<div class="border rounded-3">
  <div class="d-flex justify-content-between align-items-center p-3 border-bottom">
    <div>
      <div class="fw-medium">
        Email alerts
      </div>
      <div class="small text-body-secondary">
        Daily summary at 19:30
      </div>
    </div>
    <span class="px-2 py-1 rounded-pill small bg-success text-white">On</span> 
  </div>
  <div class="d-flex justify-content-between align-items-center p-3">
    <div>
      <div class="fw-medium">
        Push notifications
      </div>
      <div class="small text-body-secondary">
        Only mentions
      </div>
    </div>
    <span class="px-2 py-1 rounded-pill small bg-body-secondary text-body-secondary">Off</span> 
  </div>
</div>

14Announcement bar

text-bg-dark sets a contrasting text colour with the background; small and gap utilities do the rest.

New Stay somewhere unforgettable Read more

<div class="text-bg-dark rounded-3 px-3 py-2 d-flex flex-wrap align-items-center justify-content-center gap-2 small">
  <span class="badge text-bg-warning">New</span> <span>Stay somewhere unforgettable</span> <a href="#" class="link-light link-offset-2 fw-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.

All news Mountain smart update

<div class="d-flex flex-wrap gap-2">
  <span class="px-3 py-1 rounded-pill bg-primary text-white small">All</span> <span class="px-3 py-1 rounded-pill border small">news</span> <span class="px-3 py-1 rounded-pill border small">Mountain</span> <span class="px-3 py-1 rounded-pill border small">smart</span> <span class="px-3 py-1 rounded-pill border small">update</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.

Weekend getaway - secure edition

Mountain

$148.00

<div class="d-flex align-items-center gap-3 border rounded-3 p-2" style="max-width:28rem">
  <img src="../assets/img/product-9.svg" alt="Weekend getaway" width="56" height="56" class="rounded-2 object-fit-cover flex-shrink-0"> 
  <div class="flex-grow-1 overflow-hidden">
    <div class="fw-medium text-truncate">
      Weekend getaway - secure edition
    </div>
    <div class="small text-body-secondary">
      Mountain
    </div>
  </div>
  <div class="fw-bold text-nowrap">
    $148.00
  </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.

What's new in beach

Our travel insurance helps projects moving forward without extra tools. This simple workflow makes you focused on what matters on any device.

<div class="border rounded-4 p-2 p-md-4 bg-body-tertiary">
  <h3 class="h6 mb-2 mb-md-3">What&#39;s new in beach</h3>
  <p class="mb-0 small">Our travel insurance helps projects moving forward without extra tools. This simple workflow makes you focused on what matters on any device.</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="d-flex flex-wrap gap-3" 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.

Singapore

Trips designed around you

<div class="position-relative rounded-4 overflow-hidden" style="max-width:26rem">
  <img src="../assets/img/photo-8.svg" alt="Stay somewhere unforgettable" class="w-100 d-block"> 
  <div class="position-absolute bottom-0 start-0 end-0 bg-dark text-white p-3" style="--ui-bg-opacity:.6">
    <div class="small text-white-50">
      Singapore
    </div>
    <div class="fw-semibold">
      Trips designed around you
    </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

Our car rental shows you focused on what matters in just a few clicks.

<div class="d-flex flex-column align-items-center text-center py-5 px-3 border rounded-4 bg-body-tertiary">
  <div class="fs-1 text-body-tertiary mb-2">
    <i class="bi bi-folder2-open" aria-hidden="true"></i>
  </div>
  <h3 class="h6 fw-semibold mb-1">No files yet</h3>
  <p class="small text-body-secondary mb-3">Our car rental shows you focused on what matters in just a few clicks.</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>