Reducing compiled CSS size in SASS - Mini Project: Build & Apply

Reducing compiled CSS size with Sass

📖 Scenario: You are working on a website with multiple buttons that share similar styles. To keep your CSS file small and easy to maintain, you want to use Sass features to reduce repeated code.

🎯 Goal: Build a Sass stylesheet that uses variables and nesting to reduce the compiled CSS size while styling two types of buttons: .btn-primary and .btn-secondary.

📋 What You'll Learn

Create a Sass variable for the main button color

Use nesting to style .btn-primary and .btn-secondary inside a common .btn class

Use the variable for the background color of .btn-primary

Add a different background color for .btn-secondary without repeating common styles

💡 Why This Matters

🌍 Real World

Web developers often need to write CSS that is easy to maintain and small in size to improve website speed and readability.

💼 Career

Knowing how to use Sass variables, nesting, and functions is a valuable skill for front-end developers to write efficient and scalable stylesheets.

1

Create a color variable

Create a Sass variable called $main-color and set it to #3498db.

SASS

// Your code here

Hint

Use $main-color: #3498db; to create the variable.

2

Add base button styles with nesting

Create a .btn class and nest styles for .btn-primary and .btn-secondary inside it. Add padding: 1rem 2rem; and border-radius: 0.5rem; to .btn.

SASS

$main-color: #3498db;

// Your code here

Hint

Use .btn { padding: 1rem 2rem; border-radius: 0.5rem; } and nest &-primary and &-secondary inside.

3

Add background colors using the variable and a new color

Inside .btn-primary, set background-color to $main-color. Inside .btn-secondary, set background-color to #2ecc71.

SASS

$main-color: #3498db;

.btn {
  padding: 1rem 2rem;
  border-radius: 0.5rem;

  &-primary {
    // Your code here
  }

  &-secondary {
    // Your code here
  }
}

Hint

Use background-color: $main-color; for .btn-primary and background-color: #2ecc71; for .btn-secondary.

4

Add common text color and hover effect

Add color: white; to the .btn class. Then add a hover effect inside .btn-primary that changes background-color to darken($main-color, 10%) using the Sass darken() function.

SASS

$main-color: #3498db;

.btn {
  padding: 1rem 2rem;
  border-radius: 0.5rem;
  // Your code here

  &-primary {
    background-color: $main-color;
    // Your code here
  }

  &-secondary {
    background-color: #2ecc71;
  }
}

Hint

Add color: white; inside .btn and use &:hover inside &-primary with background-color: darken($main-color, 10%);.

Practice

1. Which of the following is the best way to reduce the size of compiled CSS when using Sass?

easy

A. Write very deep nesting of selectors for clarity

B. Use variables and mixins to avoid repeating the same styles

C. Add comments in Sass files to explain styles

D. Use many separate Sass files without combining them

Solution

1. Step 1: Understand Sass features for reuse

   Variables and mixins let you reuse style code instead of repeating it multiple times.

2. Step 2: Compare with other options

   Deep nesting creates many selectors increasing CSS size. Comments do not reduce CSS size. Many files without combining can increase HTTP requests.

3. Final Answer:

   Use variables and mixins to avoid repeating the same styles -> Option B

4. Quick Check:

   Reuse styles = smaller CSS [OK]

Hint: Reuse styles with variables and mixins to shrink CSS [OK]

Common Mistakes:

• Thinking deep nesting reduces CSS size
• Believing comments affect compiled CSS size
• Assuming splitting files always reduces size

2. Which Sass syntax correctly defines a mixin to reduce repeated styles?

easy

A. @function button-style() {\n padding: 1rem;\n border-radius: 0.5rem;\n}

B. @include button-style {\n padding: 1rem;\n border-radius: 0.5rem;\n}

C. @extend button-style {\n padding: 1rem;\n border-radius: 0.5rem;\n}

D. @mixin button-style {\n padding: 1rem;\n border-radius: 0.5rem;\n}

Solution

1. Step 1: Identify mixin syntax

   The correct way to define a mixin is using @mixin name { ... }.

2. Step 2: Differentiate from other directives

   @include is used to use a mixin, not define it. @function defines functions, not mixins. @extend is for inheritance, not mixin definition.

3. Final Answer:

   @mixin button-style { padding: 1rem; border-radius: 0.5rem; } -> Option D

4. Quick Check:

   Define mixin = @mixin [OK]

Hint: Define mixins with @mixin, use with @include [OK]

Common Mistakes:

• Confusing @include with @mixin for definition
• Using @function instead of @mixin
• Trying to define mixin with @extend

3. Given this Sass code, what will be the compiled CSS size impact?

$color: blue;

.button {
  color: $color;
  @include rounded-corners;
}

@mixin rounded-corners {
  border-radius: 0.5rem;
  border: 1px solid $color;
}

medium

A. The CSS will be larger because mixins duplicate code each use

B. The CSS will be smaller because styles are reused via mixin

C. The CSS will have syntax errors and not compile

D. The CSS will ignore the mixin and only use color

Solution

1. Step 1: Understand mixin behavior

   Mixins insert their styles wherever included, duplicating code each time.

2. Step 2: Analyze code impact

   Since @include rounded-corners adds border-radius and border styles inside .button, these styles are duplicated in CSS for each use.

3. Final Answer:

   The CSS will be larger because mixins duplicate code each use -> Option A

4. Quick Check:

   Mixins duplicate styles = larger CSS [OK]

Hint: Mixins duplicate styles; use carefully to reduce size [OK]

Common Mistakes:

• Assuming mixins always reduce CSS size
• Thinking variables reduce duplication inside mixins
• Believing mixins cause syntax errors here

4. This Sass code aims to reduce CSS size but causes unexpected large output. What is the error?

.card {
  .header {
    color: red;
    .title {
      font-weight: bold;
    }
  }
}

medium

A. Mixins are not included for repeated styles

B. Missing semicolons cause syntax errors

C. Nesting is too deep, creating many selectors increasing CSS size

D. Variables are not used for colors

Solution

1. Step 1: Examine nesting depth

   The code nests .header inside .card and .title inside .header, creating selectors like .card .header .title.

2. Step 2: Understand CSS size impact

   Deep nesting creates many combined selectors, increasing compiled CSS size and complexity.

3. Final Answer:

   Nesting is too deep, creating many selectors increasing CSS size -> Option C

4. Quick Check:

   Deep nesting = bigger CSS [OK]

Hint: Keep nesting shallow to avoid large CSS selectors [OK]

Common Mistakes:

• Ignoring nesting depth impact on CSS size
• Looking for syntax errors when none exist
• Thinking variables fix nesting issues

5. You want to reduce compiled CSS size by reusing button styles but avoid duplication from mixins. Which Sass feature helps achieve this best?

hard

A. Use @extend to share styles between selectors

B. Use deeply nested selectors for buttons

C. Use multiple mixins for each style property

D. Write all styles inline without variables

Solution

1. Step 1: Understand @extend behavior

   @extend shares selectors in compiled CSS, avoiding duplication by merging rules.

2. Step 2: Compare with mixins

   Mixins duplicate styles each use, increasing CSS size. @extend reuses styles without duplication.

3. Final Answer:

   Use @extend to share styles between selectors -> Option A

4. Quick Check:

   @extend shares styles, reduces CSS size [OK]

Hint: Use @extend to share styles without duplicating CSS [OK]

Common Mistakes:

• Using mixins expecting no duplication
• Nesting deeply to reuse styles
• Avoiding variables and mixins altogether