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.

Home

Style that works as hard as you do

Start in minutes and get help from a real person whenever you need it.

<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">Home</p>
  <h3 class="h5 mb-2">Style that works as hard as you do</h3>
  <p class="mb-0 text-body-secondary">Start in minutes and get help from a real person whenever you need it.</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 (the labels sit under it, so they stay readable on every step).

.35

.15

.05

<div class="d-flex flex-wrap gap-3 small text-center">
  <div>
    <div class="bg-primary rounded-2 mb-1" style="width:3.5rem;height:2.5rem;--ui-bg-opacity:1">
    </div>
    1
  </div>
  <div>
    <div class="bg-primary rounded-2 mb-1" style="width:3.5rem;height:2.5rem;--ui-bg-opacity:.6">
    </div>
    .6
  </div>
  <div>
    <div class="bg-primary rounded-2 mb-1" style="width:3.5rem;height:2.5rem;--ui-bg-opacity:.35">
    </div>
    .35
  </div>
  <div>
    <div class="bg-primary rounded-2 mb-1" style="width:3.5rem;height:2.5rem;--ui-bg-opacity:.15">
    </div>
    .15
  </div>
  <div>
    <div class="bg-primary rounded-2 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-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: fade a link that is not available yet, or fade on hover - a link people must read stays at full strength.

Loyalty rewards --ui-link-opacity:.5, not available
Member prices 100, 75 on hover
Designed to last, priced to love link-danger, faint underline

<ul class="list-unstyled mb-0 d-grid gap-2">
  <li><a href="#" class="link-primary pe-none" style="--ui-link-opacity:.5" aria-disabled="true" tabindex="-1">Loyalty rewards</a> <span class="small text-body-secondary">--ui-link-opacity:.5, not available</span></li>
  <li><a href="#" class="link-primary link-opacity-100 link-opacity-75-hover">Member prices</a> <span class="small text-body-secondary">100, 75 on hover</span></li>
  <li><a href="#" class="link-danger link-underline-opacity-25">Designed to last, priced to love</a> <span class="small text-body-secondary">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.

Felix Whitaker13 min ago

Members get early access to new drops and prices only they can see.

<div class="d-flex gap-3 align-items-start border rounded-3 p-3">
  <img src="../assets/img/avatar-12.svg" alt="Felix Whitaker" width="48" height="48" class="rounded-circle flex-shrink-0"> 
  <div class="flex-grow-1">
    <div class="d-flex justify-content-between">
      <strong>Felix Whitaker</strong><small class="text-body-secondary">13 min ago</small>
    </div>
    <p class="mb-0 small">Members get early access to new drops and prices only they can see.</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

$24,409.49

+42% this month

Customers

1.7k

-1% 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">
        $24,409.49
      </div>
      <div class="small text-success mt-1">
        <i class="bi bi-arrow-up" aria-hidden="true"></i> +42% 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">
        1.7k
      </div>
      <div class="small text-danger mt-1">
        <i class="bi bi-arrow-down" aria-hidden="true"></i> -1% 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-11.svg" alt="Freya Quinn" 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-9.svg" alt="Kai Alvarez" 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.

Shop the collection everyone talks about

Thousands of shoppers already trust us, and we work hard to keep it that way.

Get started

<div class="p-4 rounded-4 bg-primary-subtle text-center text-md-start">
  <h3 class="h4 fw-bold text-primary-emphasis">Shop the collection everyone talks about</h3>
  <p class="mb-3 text-primary-emphasis">Thousands of shoppers already trust us, and we work hard to keep it that way.</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.

Easy exchanges

Member prices

Sustainable materials

<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>Easy exchanges</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>Member prices</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>Sustainable materials</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

Free shipping on orders over $50 and easy returns within 30 days.

<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">Free shipping on orders over $50 and easy returns within 30 days.</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 14:30

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 14:30
      </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 New season, new favourites 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>New season, new favourites</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 tips Home modern project

<div class="d-flex flex-wrap gap-2">
  <span class="px-3 py-1 rounded-pill text-bg-primary small">All</span> <span class="px-3 py-1 rounded-pill border small">tips</span> <span class="px-3 py-1 rounded-pill border small">Home</span> <span class="px-3 py-1 rounded-pill border small">modern</span> <span class="px-3 py-1 rounded-pill border small">project</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.

Linen shirt - reliable edition

Apparel

$70.99

<div class="d-flex align-items-center gap-3 border rounded-3 p-2" style="max-width:28rem">
  <img src="../assets/img/product-1.svg" alt="Linen shirt" 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">
      Linen shirt - reliable edition
    </div>
    <div class="small text-body-secondary">
      Apparel
    </div>
  </div>
  <div class="fw-bold text-nowrap">
    $70.99
  </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 we choose sustainable materials

Thousands of five-star reviews from customers who came back for more. Not sure about the size? Our fit guide and live chat help you choose.

<div class="border rounded-4 p-2 p-md-4 bg-body-tertiary">
  <h3 class="h6 mb-2 mb-md-3">How we choose sustainable materials</h3>
  <p class="mb-0 small">Thousands of five-star reviews from customers who came back for more. Not sure about the size? Our fit guide and live chat help you choose.</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.

Austin

Small batches, big on quality

<div class="position-relative rounded-4 overflow-hidden" style="max-width:26rem">
  <img src="https://images.unsplash.com/photo-1573612664822-d7d347da7b80?auto=format&fit=crop&w=1200&h=800&q=70" alt="Good things, made to be used" 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">
      Austin
    </div>
    <div class="fw-semibold">
      Small batches, big on quality
    </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

Each product is checked by hand before it goes into the box.

<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">Each product is checked by hand before it goes into the box.</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>