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.

Dental

Care for the whole family

Friendly people answer your questions quickly, by phone, chat or email.

<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">Dental</p>
  <h3 class="h5 mb-2">Care for the whole family</h3>
  <p class="mb-0 text-body-secondary">Friendly people answer your questions quickly, by phone, chat or email.</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" aria-hidden="true"></i> Share</button>
    <button type="button" class="btn btn-sm btn-outline-danger"><i class="bi bi-trash3" 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.

Telehealth --ui-link-opacity:.5, not available
Online results 100, 75 on hover
Your health, our priority 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">Telehealth</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">Online results</a> <span class="small text-body-secondary">100, 75 on hover</span></li>
  <li><a href="#" class="link-danger link-underline-opacity-25">Your health, our priority</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.

Mateo Carter30 min ago

Our specialists take time to listen and explain every step of your treatment.

<div class="d-flex gap-3 align-items-start border rounded-3 p-3">
  <img src="../assets/img/avatar-5.svg" alt="Mateo Carter" width="48" height="48" class="rounded-circle flex-shrink-0"> 
  <div class="flex-grow-1">
    <div class="d-flex justify-content-between">
      <strong>Mateo Carter</strong><small class="text-body-secondary">30 min ago</small>
    </div>
    <p class="mb-0 small">Our specialists take time to listen and explain every step of your treatment.</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" 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

$28,145.95

+41% this month

Customers

3.1k

-9% 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">
        $28,145.95
      </div>
      <div class="small text-success mt-1">
        <i class="bi bi-arrow-up" aria-hidden="true"></i> +41% 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" aria-hidden="true"></i></span>
      </div>
      <div class="fs-3 fw-bold lh-1">
        3.1k
      </div>
      <div class="small text-danger mt-1">
        <i class="bi bi-arrow-down" aria-hidden="true"></i> -9% 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-5.svg" alt="Maya Ortega" 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-6.svg" alt="Finn Patel" 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.

Feel better with expert care

We keep things simple, so you can focus on what matters to you.

Get started

<div class="p-4 rounded-4 bg-primary-subtle text-center text-md-start">
  <h3 class="h4 fw-bold text-primary-emphasis">Feel better with expert care</h3>
  <p class="mb-3 text-primary-emphasis">We keep things simple, so you can focus on what matters to you.</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.

Reminders

Online results

<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>Reminders</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>Reminders</strong>
  </div>
  <div class="flex-fill p-3 rounded-3 border bg-body-tertiary">
    <i class="bi bi-cloud-arrow-up" aria-hidden="true"></i> <strong>Online results</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

Video consultations let you speak with a doctor from the comfort of home.

<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">Video consultations let you speak with a doctor from the comfort of home.</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 14:15

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 14:15
      </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 Modern healthcare close to home 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>Modern healthcare close to home</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 Cardiology clear update

<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">news</span> <span class="px-3 py-1 rounded-pill border small">Cardiology</span> <span class="px-3 py-1 rounded-pill border small">clear</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.

Vaccination - elegant edition

Pediatrics

$32.99

<div class="d-flex align-items-center gap-3 border rounded-3 p-2" style="max-width:28rem">
  <img src="../assets/img/product-5.svg" alt="Vaccination" 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">
      Vaccination - elegant edition
    </div>
    <div class="small text-body-secondary">
      Pediatrics
    </div>
  </div>
  <div class="fw-bold text-nowrap">
    $32.99
  </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.

Staying active after an injury

Friendly reminders make sure you never miss a check-up or a dose. Our clinic is fully accessible, with free parking right outside.

<div class="border rounded-4 p-2 p-md-4 bg-body-tertiary">
  <h3 class="h6 mb-2 mb-md-3">Staying active after an injury</h3>
  <p class="mb-0 small">Friendly reminders make sure you never miss a check-up or a dose. Our clinic is fully accessible, with free parking right outside.</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

Care for the whole family

<div class="position-relative rounded-4 overflow-hidden" style="max-width:26rem">
  <img src="https://images.unsplash.com/photo-1581056771107-24ca5f033842?auto=format&fit=crop&w=1200&h=800&q=70" alt="Feel better with expert care" 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">
      Care for the whole family
    </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

Same-day appointments are available for urgent needs on weekdays.

<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">Same-day appointments are available for urgent needs on weekdays.</p>
  <button type="button" class="btn btn-sm btn-primary"><i class="bi bi-cloud-arrow-up" aria-hidden="true"></i> Upload</button>
</div>