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Opal

Ratio

The ratio helper keeps a box at a fixed aspect ratio whatever its width, which is perfect for media placeholders, thumbnails, galleries and banners. Pick ratio-1x1, ratio-4x3, ratio-16x9 or ratio-21x9, or set any ratio with the --bs-aspect-ratio variable.

1The four built-in ratios

ratio-1x1, ratio-4x3, ratio-16x9 and ratio-21x9 next to each other, filled with a plain div.

1:1
4:3
16:9
21:9

2Video placeholder

A 16:9 poster image with a centred play button, ready for a video player of your choice.

Video poster

3Square product thumbnails

ratio-1x1 with object-fit-cover gives every product the same tile, whatever the photo size.

Evening meetup

Evening meetup

Group bundle

Group bundle

Virtual pass

Virtual pass

VIP pass

VIP pass

Recording pass

Recording pass

Student pass

Student pass

4Cinematic hero banner

ratio-21x9 for a wide banner with a headline overlay.

Meet the people shaping the future

The networking app helps you meet the right people before you arrive.

5Map placeholder

A 4:3 box reserved for a map, showing the address until the map loads.

Opal22 Lakeview Terrace, Singapore

6Custom 3:2 photo

Any ratio works with the --bs-aspect-ratio variable: 2 / 3 = 66.67% for classic photo prints.

Joining online: how the virtual pass works
3:2 · How to choose the right ticket

7Portrait team cards

A 3:4 portrait ratio (133.33%) for team photos in cards.

Ravi Patel

Ravi Patel

HR Partner

Sofia Kowalski

Sofia Kowalski

Project Manager

Amara Rossi

Amara Rossi

QA Engineer

8Vertical stories

A 9:16 ratio (177.78%) for phone sized stories or short clips in a scrolling row.

Story by Jonah SilvaJonah
Story by Freya WhitakerFreya
Story by Samir NguyenSamir
Story by Hana AshfordHana

9Chart area

A 16:9 box that keeps a simple bar chart in proportion on every screen.

Monthly bookings

10Blog card cover

ratio-16x9 as a card image keeps every post card in a grid the same height.

Highlights from last year's workshops
release

How to pitch a talk that gets accepted

Apr 18, 2026

11Caption over a gradient

A 4:3 image with a gradient overlay so white caption text stays readable.

CopenhagenSpeaker management

12Mixed ratio gallery

Combining 1:1, 4:3 and 16:9 tiles in one responsive grid.

Gallery photo 1
Gallery photo 2
Gallery photo 3
Gallery photo 4

13Thumbnails in table cells

A small ratio-1x1 box keeps order line images square inside a table.

ImageItemPrice
Early bird pass
Early bird pass$277.99
Student pass
Student pass$155.99
Masterclass
Masterclass$264.00

14Empty cover placeholder

A dashed 4:3 area that reserves space for an image that has not been chosen yet.

No cover image yet

15Colour swatches

Empty square ratios make perfect colour swatches for a style guide.

primary

primary

secondary

secondary

success

success

info

info

warning

warning

danger

danger

16Video thumbnails with badges

Duration and status badges positioned over 16:9 thumbnails.

8:11New

How to get the most out of a conference

3:09

What we learned from last year's feedback

9:57

A guide to the city for visiting attendees

17Media list

Fixed width 4:3 thumbnails beside article titles in a reading list.

  • Looking back at a busy season

    Jan 24, 2026 · 11 min read

  • Our favourite tips for busy weeks

    Mar 1, 2026 · 11 min read

  • A beginner's guide to getting started

    Jul 3, 2026 · 12 min read

18Responsive ratio

A small custom class changes --bs-aspect-ratio per breakpoint: square on phones, 21:9 on tablets and up.

Learn, connect and get inspired

19Round avatars

ratio-1x1 with rounded-circle keeps profile pictures perfectly round even when the source is not square.

Leo Lindqvist
Leo
Ava Haddad
Ava
Lucas Fischer
Lucas
Ruby Whitaker
Ruby

20Loading skeleton

A 16:9 placeholder block with placeholder-glow while the real image and text load.

The skeleton reserves the exact space, so the page does not jump when content arrives.