Ratio utilities for embeds in Bootsrap - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of Bootstrap's ratio utilities for embeds?

They help keep embedded content like videos or iframes at a consistent aspect ratio, so they resize nicely on different screen sizes without distortion.

beginner

Which Bootstrap class sets a 16:9 aspect ratio for embedded content?

The class .ratio-16x9 sets the aspect ratio to 16:9 for embedded elements.

beginner

How do you make an iframe responsive with Bootstrap ratio utilities?

Wrap the <code>&lt;iframe&gt;</code> inside a container with a ratio class like <code>.ratio-16x9</code>. This container controls the aspect ratio and makes the iframe resize properly.

beginner

Name two aspect ratios available by default in Bootstrap ratio utilities.

Bootstrap provides .ratio-16x9 and .ratio-4x3 by default for common video aspect ratios.

intermediate

How can you create a custom aspect ratio using Bootstrap's ratio utilities?

You can use the <code>.ratio</code> class with a custom CSS variable <code>--bs-aspect-ratio</code> set to the desired percentage to define a custom aspect ratio.

Which Bootstrap class would you use to make an embedded video keep a 4:3 ratio?

A .ratio-16x9

B .embed-responsive-4by3

C .ratio-4x3

D .video-responsive

Bootstrap uses .ratio-4x3 to keep a 4:3 aspect ratio for embedded content.

What HTML element should be wrapped inside a Bootstrap ratio container to make it responsive?

A button

B div

C span

D iframe

iframes are commonly wrapped inside a ratio container to keep their aspect ratio responsive.

How does Bootstrap control the aspect ratio in ratio utilities?

A Using padding-top percentage based on aspect ratio

B Using fixed width and height

C Using JavaScript to resize

D Using margin auto

Bootstrap uses padding-top with a percentage to maintain the aspect ratio responsively.

Which class is the base class for all ratio utilities in Bootstrap?

A .embed-responsive

B .ratio

C .responsive-video

D .aspect-ratio

The .ratio class is the base class for Bootstrap's ratio utilities.

To create a custom aspect ratio, which CSS variable is used with the .ratio class?

A --bs-aspect-ratio

B --aspect-ratio

C --ratio-value

D --embed-ratio

Bootstrap uses the --bs-aspect-ratio CSS variable to set custom aspect ratios.

Explain how Bootstrap's ratio utilities help make embedded videos responsive.

Think about how the container controls height relative to width.

Describe how to create a custom aspect ratio for an embed using Bootstrap classes and CSS variables.

Custom ratios use CSS variables with the base .ratio class.

Practice

1. What is the main purpose of Bootstrap's ratio utility classes like ratio-16x9?

easy

A. To change the background color of embedded content

B. To add borders around embedded content

C. To keep embedded videos or iframes responsive and maintain their aspect ratio

D. To add padding inside embedded content

Solution

1. Step 1: Understand the purpose of ratio utilities

   Bootstrap's ratio utilities are designed to keep embedded content like videos or iframes responsive by maintaining a fixed aspect ratio.

2. Step 2: Identify what ratio classes do

   Classes like ratio-16x9 set the width and height ratio so the content scales properly on different screen sizes.

3. Final Answer:

   To keep embedded videos or iframes responsive and maintain their aspect ratio -> Option C

4. Quick Check:

   Ratio utilities = responsive aspect ratio [OK]

Hint: Ratio classes keep embeds sized correctly on all screens [OK]

Common Mistakes:

• Thinking ratio classes add borders or colors
• Confusing ratio with padding or margin utilities
• Using ratio classes without wrapping content in a div

2. Which is the correct HTML structure to use Bootstrap's ratio utility for a 4:3 embedded video?

easy

A.

B.

C.

D.

Solution

1. Step 1: Check the required wrapper and classes

   Bootstrap requires a div with class ratio plus the aspect ratio class like ratio-4x3 wrapping the embedded content.

2. Step 2: Verify the iframe is inside the wrapper

   The iframe should not have the ratio class directly; it must be inside the div with the ratio classes.

3. Final Answer:

   <div class='ratio ratio-4x3'><iframe src='video.mp4'></iframe></div> -> Option A

4. Quick Check:

   Wrapper div with ratio classes = correct syntax [OK]

Hint: Wrap iframe in div with both 'ratio' and ratio-size classes [OK]

Common Mistakes:

• Applying ratio class directly on iframe
• Missing the 'ratio' base class on the wrapper div
• Using only one class without the other

3. What will be the visual result of this code snippet?

<div class='ratio ratio-1x1'>
  <iframe src='https://example.com' title='Example'></iframe>
</div>

medium

A. An iframe with fixed width and height ignoring screen size

B. A rectangular iframe with 16:9 ratio

C. An iframe that overflows outside the container

D. A square embedded iframe that scales responsively

Solution

1. Step 1: Understand the ratio-1x1 class effect

   The class ratio-1x1 sets the aspect ratio to 1:1, which means width equals height, making the embed square.

2. Step 2: Recognize responsive scaling behavior

   Because it's wrapped in a div with ratio classes, the iframe scales responsively to fit its container while keeping the square shape.

3. Final Answer:

   A square embedded iframe that scales responsively -> Option D

4. Quick Check:

   ratio-1x1 = square responsive embed [OK]

Hint: ratio-1x1 means square shape that scales with container [OK]

Common Mistakes:

• Confusing 1x1 with 16x9 ratio
• Thinking iframe size is fixed
• Ignoring the responsive wrapper effect

4. Identify the error in this Bootstrap embed code:

<div class='ratio-16x9'>
  <iframe src='video.mp4'></iframe>
</div>

medium

A. The iframe tag is not closed properly

B. Missing the base class ratio on the wrapper div

C. The ratio class should be on the iframe, not the div

D. The src attribute value is invalid

Solution

1. Step 1: Check the required classes for ratio utility

   Bootstrap requires the wrapper div to have the base class ratio along with the aspect ratio class like ratio-16x9.

2. Step 2: Verify the given code

   The div only has ratio-16x9 but is missing the base ratio class, so the aspect ratio styling won't apply correctly.

3. Final Answer:

   Missing the base class ratio on the wrapper div -> Option B

4. Quick Check:

   Always include 'ratio' base class with ratio-size class [OK]

Hint: Always use both 'ratio' and ratio-size classes on wrapper div [OK]

Common Mistakes:

• Using ratio class on iframe instead of div
• Forgetting to add the base 'ratio' class
• Assuming iframe needs ratio classes

5. You want to embed a video that should always appear as a perfect square on all devices, but also add a subtle shadow around it. Which Bootstrap classes and structure should you use?

hard

A. <div class='ratio ratio-1x1 shadow-sm'><iframe src='video.mp4' title='Video'></iframe></div>

B. <iframe class='ratio-1x1 shadow-sm' src='video.mp4' title='Video'></iframe>

C. <div class='ratio-16x9 shadow-sm'><iframe src='video.mp4' title='Video'></iframe></div>

D. <div class='shadow-sm'><iframe class='ratio ratio-1x1' src='video.mp4' title='Video'></iframe></div>

Solution

1. Step 1: Choose the correct ratio class for a square

   The class ratio-1x1 ensures the embed is a perfect square on all devices.

2. Step 2: Add shadow styling correctly

   The shadow utility shadow-sm should be added to the same wrapper div that holds the ratio classes to apply the shadow around the embed.

3. Step 3: Confirm correct HTML structure

   The iframe should be inside the div with both ratio and shadow-sm classes. Applying ratio classes directly on iframe is incorrect.

4. Final Answer:

   <div class='ratio ratio-1x1 shadow-sm'><iframe src='video.mp4' title='Video'></iframe></div> -> Option A

5. Quick Check:

   Wrapper div with ratio and shadow classes = correct [OK]

Hint: Add shadow class to ratio wrapper div for styling [OK]

Common Mistakes:

• Putting ratio classes on iframe instead of div
• Using wrong ratio class for square shape
• Adding shadow to iframe instead of wrapper