Bootstrap SASS variable overrides - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of overriding Bootstrap SASS variables?

Overriding Bootstrap SASS variables lets you customize Bootstrap's default styles like colors, fonts, and spacing before compiling the CSS. This way, you can change the look of your site without editing Bootstrap's core files.

beginner

Where should you place your Bootstrap SASS variable overrides?

You should place your variable overrides in a separate SASS file before importing Bootstrap's main SASS files. This ensures your custom values replace the defaults during compilation.

beginner

How do you override the primary color variable in Bootstrap SASS?

You write:

$primary: #ff6600;

before importing Bootstrap's SASS files. This changes the primary color to a bright orange throughout your site.

intermediate

Why is it important to override variables before importing Bootstrap SASS files?

Bootstrap uses the variable values when compiling its styles. If you override variables after importing, your changes won't affect the compiled CSS. Overriding first ensures your values are used.

beginner

Can you override Bootstrap SASS variables without modifying Bootstrap source files?

Yes! You create your own SASS file with variable overrides and then import Bootstrap's SASS. This keeps Bootstrap files untouched and makes updates easier.

Where do you place your Bootstrap SASS variable overrides?

A Inside Bootstrap's compiled CSS file

B After importing Bootstrap SASS files

C Before importing Bootstrap SASS files

D In the HTML file

Variable overrides must be set before importing Bootstrap SASS so they affect the compiled CSS.

How do you change Bootstrap's primary color using SASS?

A $primary: #ff6600;

B primary-color: #ff6600;

C color-primary = #ff6600;

D set-primary-color(#ff6600);

Bootstrap uses SASS variables like $primary to define colors. Assigning a new value overrides it.

What happens if you override variables after importing Bootstrap SASS?

A Overrides change the CSS immediately

B Overrides have no effect on compiled CSS

C Bootstrap throws an error

D CSS file size doubles

Bootstrap compiles CSS using variables at import time, so later overrides don't affect the output.

Why is it better to override variables in your own file rather than editing Bootstrap source?

A Keeps Bootstrap files unchanged for easy updates

B Bootstrap source files are read-only

C Overrides only work outside Bootstrap files

D Bootstrap source files are in JavaScript

Keeping Bootstrap source files untouched helps maintainability and simplifies upgrades.

Which of these is NOT a common Bootstrap SASS variable to override?

A $font-family-base

B $primary

C $container-padding

D $html-tag

$html-tag is not a Bootstrap SASS variable; the others control fonts, colors, and spacing.

Explain how to customize Bootstrap styles using SASS variable overrides.

Think about the order of your code and how Bootstrap uses variables.

Why should you avoid editing Bootstrap's original SASS files when customizing variables?

Consider maintenance and future updates.

Practice

1. What is the correct way to override a Bootstrap SASS variable like $primary color?

easy

A. Set $primary before importing Bootstrap's SASS files

B. Set $primary after importing Bootstrap's SASS files

C. Change the CSS file directly without using SASS variables

D. Override $primary inside the compiled CSS file

Solution

1. Step 1: Understand Bootstrap SASS variable loading

   Bootstrap uses SASS variables during compilation, so variables must be set before importing Bootstrap's SASS files to take effect.

2. Step 2: Apply variable override before import

   By setting $primary before the import, Bootstrap uses the new value instead of the default.

3. Final Answer:

   Set $primary before importing Bootstrap's SASS files -> Option A

4. Quick Check:

   Override variables before import = A [OK]

Hint: Always set variables before importing Bootstrap [OK]

Common Mistakes:

• Setting variables after importing Bootstrap
• Editing compiled CSS instead of SASS variables
• Trying to override variables in CSS files

2. Which of the following is the correct syntax to override the Bootstrap SASS variable $font-size-base to 1.25rem?

easy

A. $font-size-base: 1.25rem !default;

B. $font-size-base: 1.25rem;

C. font-size-base: 1.25rem;

D. $font-size-base = 1.25rem;

Solution

1. Step 1: Recall SASS variable syntax

   SASS variables use $variable-name: value; syntax without equals sign or !default when overriding.

2. Step 2: Identify correct override syntax

   To override, simply assign $font-size-base: 1.25rem; before importing Bootstrap.

3. Final Answer:

   $font-size-base: 1.25rem; -> Option B

4. Quick Check:

   SASS variable override syntax = D [OK]

Hint: Use colon and semicolon, no equals sign for SASS variables [OK]

Common Mistakes:

• Using equals sign instead of colon
• Adding !default when overriding
• Omitting the $ sign before variable name

3. Given this SASS code snippet, what will be the background color of a Bootstrap button?

$btn-primary-bg: #ff0000;
@import 'bootstrap';

medium

A. Black

B. Default Bootstrap blue

C. Transparent

D. Red (#ff0000)

Solution

1. Step 1: Check variable override before import

   The variable $btn-primary-bg is set to red before importing Bootstrap, so Bootstrap uses this value.

2. Step 2: Understand Bootstrap button background

   Bootstrap buttons use $btn-primary-bg for the primary button background color.

3. Final Answer:

   Red (#ff0000) -> Option D

4. Quick Check:

   Override variable before import changes button color = A [OK]

Hint: Override color variables before import to change styles [OK]

Common Mistakes:

• Expecting default color despite override
• Setting variable after import
• Confusing variable names

4. You tried to override $spacer to 3rem but your Bootstrap layout spacing did not change. What is the most likely mistake?

medium

A. A, B, and D

B. You used $spacer = 3rem; instead of colon syntax

C. You set $spacer after importing Bootstrap SASS files

D. You forgot to recompile your SASS files after changes

Solution

1. Step 1: Check variable override timing

   Setting $spacer after importing Bootstrap has no effect because variables must be set before import.

2. Step 2: Verify syntax and compilation

   Using equals sign is invalid syntax and forgetting to recompile means changes won't apply.

3. Step 3: Combine all errors

   Any of these mistakes can cause the override to fail, so all are likely causes.

4. Final Answer:

   A, B, and D -> Option A

5. Quick Check:

   Timing, syntax, and compilation errors cause override failure = C [OK]

Hint: Check override order, syntax, and recompile after changes [OK]

Common Mistakes:

• Setting variables after import
• Using wrong syntax with equals sign
• Not recompiling SASS after changes

5. You want to customize Bootstrap's primary color and font size but keep your changes easy to update later. Which approach is best?

hard

A. Edit Bootstrap's original SASS files directly to change variables

B. Override variables in CSS after Bootstrap is loaded

C. Create a separate SASS file that sets $primary and $font-size-base before importing Bootstrap

D. Use JavaScript to change styles dynamically after page load

Solution

1. Step 1: Understand maintainability best practices

   Editing Bootstrap's original files makes updates hard and error-prone.

2. Step 2: Use separate SASS file for overrides

   Setting variables in a separate file before importing Bootstrap keeps customizations clean and easy to update.

3. Step 3: Avoid CSS or JS overrides for variables

   CSS overrides can't change SASS variables, and JS changes styles after load, not at compile time.

4. Final Answer:

   Create a separate SASS file that sets $primary and $font-size-base before importing Bootstrap -> Option C

5. Quick Check:

   Separate override file before import = B [OK]

Hint: Keep overrides separate and before import for easy updates [OK]

Common Mistakes:

• Editing Bootstrap source files directly
• Trying to override variables in CSS
• Using JavaScript for style changes instead of SASS