Content blocks with @content in SASS

Introduction

Content blocks with @content let you pass a chunk of styles into a mixin. This helps you reuse code and keep your styles organized.

You want to create a reusable style wrapper that can accept different inner styles.

You need to apply common styles but customize some parts inside.

You want to keep your CSS DRY (Don't Repeat Yourself) by sharing style blocks.

You want to write cleaner and more readable Sass code by separating concerns.

Syntax

SASS

@mixin mixin-name {
  /* common styles here */
  @content;
}

The @content directive is a placeholder for styles passed when you include the mixin.

You use @include mixin-name { ... } to pass the styles inside the curly braces.

Examples

This mixin adds a border and padding, then inserts extra styles like background color.

SASS

@mixin box {
  border: 1px solid black;
  padding: 1rem;
  @content;
}

.container {
  @include box {
    background-color: lightblue;
  }
}

The mixin sets font weight, and the included block adds color and background.

SASS

@mixin button-style {
  font-weight: bold;
  @content;
}

.button {
  @include button-style {
    color: white;
    background-color: blue;
  }
}

Sample Program

This example creates a card mixin with border, padding, and background color. The @content lets you add extra styles when you include it. The .article and .note classes use the mixin but add their own unique styles inside the block.

SASS

@use 'sass:color';

@mixin card {
  border: 2px solid black;
  padding: 1.5rem;
  border-radius: 0.5rem;
  background-color: color.scale(white, $lightness: -10%);
  @content;
}

.article {
  @include card {
    box-shadow: 0 0.5rem 1rem rgba(0, 0, 0, 0.1);
  }
}

.note {
  @include card {
    background-color: color.scale(yellow, $lightness: -20%);
    font-style: italic;
  }
}

Important Notes

You can only use @content inside mixins, not in regular selectors.

If you don't pass any content when including the mixin, @content is simply ignored.

Using @content helps keep your Sass modular and easier to maintain.

Summary

@content lets you pass custom styles into a mixin.

Use it to create flexible, reusable style blocks.

It keeps your code clean and avoids repetition.

Practice

1. What is the main purpose of @content in Sass?

easy

A. To pass custom styles into a mixin for flexible reuse

B. To define variables inside a mixin

C. To import external CSS files

D. To create loops in Sass

Solution

1. Step 1: Understand what @content does

   @content allows you to insert custom CSS blocks inside a mixin, making it flexible.

2. Step 2: Compare with other options

   Variables, imports, and loops are different Sass features unrelated to @content.

3. Final Answer:

   To pass custom styles into a mixin for flexible reuse -> Option A

4. Quick Check:

   @content = custom styles in mixin [OK]

Hint: Remember: @content inserts custom styles inside mixins [OK]

Common Mistakes:

• Confusing @content with variables or imports
• Thinking @content creates loops
• Assuming @content is for defining selectors

2. Which of the following is the correct syntax to use @content inside a mixin?

easy

A. @mixin example { @include content; }

B. @mixin example { content(); }

C. @mixin example { @content; }

D. @mixin example { content; }

Solution

1. Step 1: Recall the syntax for content blocks

   Inside a mixin, @content; is used to insert the passed block.

2. Step 2: Check each option

   Only @mixin example { @content; } uses @content; correctly with the semicolon.

3. Final Answer:

   @mixin example { @content; } -> Option C

4. Quick Check:

   Correct syntax uses @content; inside mixin [OK]

Hint: Use @content; with a semicolon inside mixins [OK]

Common Mistakes:

• Omitting the @ symbol before content
• Using parentheses like a function call
• Forgetting the semicolon after @content

3. What will be the output CSS of this Sass code?

@mixin card {
  border: 1px solid black;
  padding: 1rem;
  @content;
}

.box {
  @include card {
    background-color: yellow;
  }
}

medium

A. .box { border: 1px solid black; padding: 1rem; } .box { background-color: yellow; }

B. .box { border: 1px solid black; padding: 1rem; background-color: yellow; }

C. .box { background-color: yellow; }

D. Syntax error, no output

Solution

1. Step 1: Understand mixin with @content

   The mixin card adds border and padding, then inserts the passed block with @content.

2. Step 2: Check how .box includes the mixin

   The block inside @include card { ... } adds background-color: yellow; inside the mixin's content.

3. Final Answer:

   .box { border: 1px solid black; padding: 1rem; background-color: yellow; } -> Option B

4. Quick Check:

   Mixin + @content block = combined styles [OK]

Hint: Mixin styles + @content block styles combine inside selector [OK]

Common Mistakes:

• Thinking @content styles appear outside the selector
• Expecting separate CSS blocks for mixin and content
• Assuming syntax error due to block usage

4. Identify the error in this Sass code using @content:

@mixin highlight {
  background: yellow;
  @content
}

.text {
  @include highlight {
    color: red;
  }
}

medium

A. Missing semicolon after @content

B. Mixin name should be @content

C. Cannot use blocks with @include

D. Background property is invalid

Solution

1. Step 1: Check syntax of @content inside mixin

   @content must end with a semicolon to be valid.

2. Step 2: Verify other parts

   Mixin name and block usage are correct; background property is valid CSS.

3. Final Answer:

   Missing semicolon after @content -> Option A

4. Quick Check:

   @content requires semicolon [OK]

Hint: Always put semicolon after @content inside mixins [OK]

Common Mistakes:

• Omitting semicolon after @content
• Confusing mixin and content names
• Thinking block usage with @include is invalid

5. You want to create a reusable button style mixin that allows custom hover styles using @content. Which Sass code correctly achieves this?

hard

A. @mixin button { padding: 1rem; border: none; @content; &:hover { @content; } }

B. @mixin button { padding: 1rem; border: none; @content; } .btn:hover { @content; }

C. @mixin button { padding: 1rem; border: none; } .btn { @include button; &:hover { @content; } }

D. @mixin button { padding: 1rem; border: none; @content; &:hover { @content; } } .btn { @include button { color: blue; &:hover { color: red; } } }

Solution

1. Step 1: Understand the goal

   Create a mixin that sets base button styles and allows custom styles including hover via @content.

2. Step 2: Analyze each option

   @mixin button { padding: 1rem; border: none; @content; &:hover { @content; } } .btn { @include button { color: blue; &:hover { color: red; } } } defines the mixin with @content inside and inside &:hover, then includes it with a block that passes normal and hover styles. This correctly applies custom hover styles.

3. Step 3: Why others fail

   @mixin button { padding: 1rem; border: none; @content; &:hover { @content; } } tries to use @content twice in the mixin without passing blocks properly. @mixin button { padding: 1rem; border: none; @content; } .btn:hover { @content; } applies hover styles outside the mixin, losing reusability. @mixin button { padding: 1rem; border: none; } .btn { @include button; &:hover { @content; } } misuses @content outside mixin context.

4. Final Answer:

   @mixin button { padding: 1rem; border: none; @content; &:hover { @content; } } .btn { @include button { color: blue; &:hover { color: red; } } } -> Option D

5. Quick Check:

   Mixin with @content block for hover = @mixin button { padding: 1rem; border: none; @content; &:hover { @content; } } .btn { @include button { color: blue; &:hover { color: red; } } } [OK]

Hint: Pass hover styles inside @include block with nested &:hover [OK]

Common Mistakes:

• Using @content outside mixin
• Trying to call @content multiple times without blocks
• Defining hover styles outside mixin losing flexibility