Custom breakpoints in Bootsrap - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a breakpoint in Bootstrap?

A breakpoint is a screen width where the layout changes to better fit the device, like switching from a phone view to a tablet or desktop view.

intermediate

How do you define a custom breakpoint in Bootstrap?

You add or change breakpoint values in Bootstrap's Sass variables before compiling the CSS, for example by setting new widths in the $grid-breakpoints map.

beginner

Why use custom breakpoints instead of default ones?

Custom breakpoints let you tailor your design to specific device sizes or layouts, making your site look better on unusual screen widths.

intermediate

Show the Sass code snippet to add a custom breakpoint named 'xxl' at 1400px.

$grid-breakpoints: ( xs: 0, sm: 576px, md: 768px, lg: 992px, xl: 1200px, xxl: 1400px );

beginner

How do you use a custom breakpoint class in HTML after defining it?

Use the breakpoint name in class names like <code>col-xxl-6</code> to apply styles starting at the 'xxl' breakpoint width.

What file do you modify to add custom breakpoints in Bootstrap?

A HTML file

B Sass variables file

C JavaScript file

D Bootstrap CSS file directly

Custom breakpoints are set in the Sass variables before compiling Bootstrap CSS.

Which Bootstrap class uses the 'lg' breakpoint?

A col-sm-4

B col-xl-4

C col-lg-4

D col-xs-4

The 'lg' breakpoint is used in classes like col-lg-4 to apply styles at large screen widths.

What is the default width for the 'md' breakpoint in Bootstrap 5?

A 768px

B 992px

C 576px

D 1200px

The 'md' breakpoint starts at 768px by default.

If you add a custom breakpoint 'xxl' at 1400px, how do you apply a column width at that breakpoint?

A Use class col-xxl-*

B Use class col-xl-*

C Use class col-lg-*

D Use class col-sm-*

Custom breakpoint names are used in class names like col-xxl-*.

Why should you recompile Bootstrap CSS after changing breakpoints?

A No need to recompile

B To update JavaScript functionality

C To change HTML structure automatically

D To apply the new breakpoint settings in the CSS

Bootstrap CSS must be recompiled to include changes made in Sass variables.

Explain how to create and use a custom breakpoint in Bootstrap.

Think about Sass variables and class naming.

Why are custom breakpoints useful in responsive design?

Consider different screen sizes and design needs.

Practice

1. What is the main purpose of custom breakpoints in Bootstrap?

easy

A. To disable responsive design completely

B. To change the colors of Bootstrap components

C. To add new fonts to the Bootstrap theme

D. To define new screen widths where the layout changes

Solution

1. Step 1: Understand what breakpoints do

   Breakpoints tell Bootstrap when to change layout based on screen size.

2. Step 2: Identify the role of custom breakpoints

   Custom breakpoints let you add or change these screen widths to better fit your design.

3. Final Answer:

   To define new screen widths where the layout changes -> Option D

4. Quick Check:

   Custom breakpoints = new layout widths [OK]

Hint: Breakpoints control layout changes by screen size [OK]

Common Mistakes:

• Thinking breakpoints change colors or fonts
• Confusing breakpoints with disabling responsiveness
• Assuming breakpoints only affect mobile views

2. Which SCSS variable would you modify to add a new custom breakpoint in Bootstrap?

easy

A. $grid-breakpoints

B. $colors

C. $font-family-base

D. $container-max-widths

Solution

1. Step 1: Identify SCSS variables related to breakpoints

   Bootstrap uses $grid-breakpoints to define screen widths for breakpoints.

2. Step 2: Confirm which variable controls breakpoints

   Modifying $grid-breakpoints lets you add or change custom breakpoints.

3. Final Answer:

   $grid-breakpoints -> Option A

4. Quick Check:

   Breakpoint variable = $grid-breakpoints [OK]

Hint: Breakpoints are set in $grid-breakpoints SCSS variable [OK]

Common Mistakes:

• Changing $colors instead of breakpoints
• Modifying font or container width variables
• Trying to add breakpoints in CSS instead of SCSS

3. Given this SCSS snippet, what is the minimum screen width for the custom breakpoint xxl?

$grid-breakpoints: (
  xs: 0,
  sm: 576px,
  md: 768px,
  lg: 992px,
  xl: 1200px,
  xxl: 1400px
);

medium

A. 1200px

B. 1400px

C. 992px

D. 768px

Solution

1. Step 1: Locate the xxl key in the map

   The map shows xxl: 1400px, meaning the breakpoint starts at 1400 pixels.

2. Step 2: Understand breakpoint meaning

   Bootstrap applies styles for xxl at screen widths 1400px and above.

3. Final Answer:

   1400px -> Option B

4. Quick Check:

   xxl breakpoint = 1400px [OK]

Hint: Check the value next to the breakpoint name [OK]

Common Mistakes:

• Confusing breakpoint names with values
• Picking the previous breakpoint's width
• Ignoring the unit (px) in values

4. You added a custom breakpoint xxl at 1400px but your styles for it are not applying. What is the most likely mistake?

medium

A. You forgot to import Bootstrap SCSS after setting the breakpoint

B. You defined xxl inside $colors variable

C. You used @media (min-width: 1400) without units

D. You wrote CSS inside body instead of html

Solution

1. Step 1: Check common syntax errors in media queries

   Media queries require units like px for widths, missing units cause failure.

2. Step 2: Identify the error in the options

   You used @media (min-width: 1400) without units shows @media (min-width: 1400) missing px, so styles won't apply.

3. Final Answer:

   You used @media (min-width: 1400) without units -> Option C

4. Quick Check:

   Media query units required [OK]

Hint: Always include units like px in media queries [OK]

Common Mistakes:

• Forgetting units in media queries
• Not importing Bootstrap SCSS after changes
• Defining breakpoints in wrong variables
• Confusing CSS selectors with media queries

5. You want to add a custom breakpoint at 1600px named xxxl. Which SCSS code correctly adds it and sets container max width for it?

hard

A. $grid-breakpoints: map-merge($grid-breakpoints, (xxxl: 1600px));
$container-max-widths: map-merge($container-max-widths, (xxxl: 1540px));

B. $grid-breakpoints: (xxxl: 1600px);
$container-max-widths: (xxxl: 1540px);

C. $grid-breakpoints: map-merge($colors, (xxxl: 1600px));
$container-max-widths: map-merge($container-max-widths, (xxxl: 1540px));

D. $grid-breakpoints: map-merge($grid-breakpoints, (xxxl: 1600));
$container-max-widths: map-merge($container-max-widths, (xxxl: 1540));

Solution

1. Step 1: Add new breakpoint using map-merge

   Use map-merge to add xxxl: 1600px to existing $grid-breakpoints.

2. Step 2: Set container max width for new breakpoint

   Similarly, add xxxl: 1540px to $container-max-widths using map-merge.

3. Step 3: Check for correct syntax and units

   $grid-breakpoints: map-merge($grid-breakpoints, (xxxl: 1600px)); $container-max-widths: map-merge($container-max-widths, (xxxl: 1540px)); uses correct variables, map-merge, and includes units px.

4. Final Answer:

   Correctly merges new breakpoint and container width with units -> Option A

5. Quick Check:

   Use map-merge with units for custom breakpoints [OK]

Hint: Use map-merge with px units to add breakpoints [OK]

Common Mistakes:

• Overwriting variables instead of merging
• Missing px units in values
• Merging into wrong variables like $colors
• Using incomplete or invalid SCSS syntax