Lighten and darken functions in SASS - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the lighten() function do in Sass?

It makes a color lighter by increasing its lightness by a given percentage.

beginner

How does the darken() function affect a color in Sass?

It makes a color darker by decreasing its lightness by a given percentage.

beginner

Write a Sass code snippet to lighten a blue color by 20%.

$light-blue: lighten(blue, 20%);

intermediate

What happens if you use darken($color, 100%) in Sass?

The color becomes completely black because lightness is reduced to 0%.

intermediate

Why is it better to use lighten() and darken() instead of hardcoding colors?

Because they keep color relationships consistent and make it easier to adjust themes by changing base colors.

What parameter does the lighten() function take besides the color?

A A percentage to increase lightness

B A hex code

C A font size

D A pixel value

The lighten() function takes a color and a percentage to increase its lightness.

If you want to make a color darker by 10%, which function do you use?

A fade-out()

B lighten()

C saturate()

D darken()

The darken() function decreases the lightness of a color by the given percentage.

What will lighten(red, 0%) return?

A The same red color

B A lighter red

C A darker red

D White

Using 0% means no change, so the color stays the same.

Which CSS property can be affected by using lighten() and darken() in Sass?

A font-family

B background-color

C margin

D border-width

These functions change colors, so they affect properties like background-color.

What is the range of the percentage value used in lighten() and darken()?

A 1 to 10

B 0 to 255

C 0% to 100%

D Any negative number

The percentage must be between 0% (no change) and 100% (full lightness or darkness).

Explain how the lighten() and darken() functions work in Sass and give an example of each.

Think about how colors get lighter or darker by changing their lightness.

Why is using lighten() and darken() functions helpful when designing a website's color theme?

Consider how changing one base color can update many related colors.

Practice

1. What does the lighten() function do in Sass?

easy

A. Changes a color to grayscale

B. Makes a color darker by decreasing its brightness

C. Inverts the color completely

D. Makes a color lighter by increasing its brightness

Solution

1. Step 1: Understand the purpose of lighten()

   The lighten() function increases the lightness of a color, making it appear lighter.

2. Step 2: Compare with other options

   Other options describe darkening, grayscale, or inversion, which are not what lighten() does.

3. Final Answer:

   Makes a color lighter by increasing its brightness -> Option D

4. Quick Check:

   lighten() = makes color lighter [OK]

Hint: Lighten means make color brighter or lighter [OK]

Common Mistakes:

• Confusing lighten() with darken()
• Thinking lighten() changes color hue
• Assuming lighten() inverts colors

2. Which of the following is the correct syntax to darken a color by 20% in Sass?

easy

A. darken(20%, #3498db)

B. darken(#3498db 20%)

C. darken(#3498db, 20%)

D. darken(#3498db; 20%)

Solution

1. Step 1: Recall function syntax

   The darken() function takes two arguments: a color and a percentage, in that order, separated by a comma.

2. Step 2: Check each option

   darken(#3498db, 20%) matches the correct syntax: darken(#3498db, 20%). Others have wrong order or missing comma/semicolon.

3. Final Answer:

   darken(#3498db, 20%) -> Option C

4. Quick Check:

   darken(color, percent) syntax [OK]

Hint: Function args: color first, then percentage with comma [OK]

Common Mistakes:

• Swapping argument order
• Omitting comma between arguments
• Using semicolon instead of comma

3. What color will be produced by this Sass code?

$base-color: #800000;
$light-color: lighten($base-color, 50%);
body { background-color: $light-color; }

medium

A. A very dark red color

B. A very light pinkish color

C. Pure white

D. Bright green

Solution

1. Step 1: Understand lighten effect on #800000

   The base color #800000 is a dark red. Lightening it by 50% will add a lot of white, making it much lighter and pinkish.

2. Step 2: Eliminate other options

   It won't be dark (B), pure white (C), or green (D) because lighten only adds lightness to the original red color.

3. Final Answer:

   A very light pinkish color -> Option B

4. Quick Check:

   lighten dark red by 50% = light pink [OK]

Hint: Lighten dark red by 50% = light pinkish color [OK]

Common Mistakes:

• Thinking lighten makes color darker
• Confusing lighten with color inversion
• Expecting pure white after lighten

4. Identify the error in this Sass code:

$color: #123456;
$dark: darken($color 30%);
.button { background: $dark; }

medium

A. Missing comma between arguments in darken()

B. Invalid color code #123456

C. darken() cannot be used inside variables

D. Percentage should be without % sign

Solution

1. Step 1: Check darken() function syntax

   The darken() function requires a comma between the color and percentage arguments.

2. Step 2: Identify the missing comma

   In the code, darken($color 30%) lacks a comma, causing a syntax error.

3. Final Answer:

   Missing comma between arguments in darken() -> Option A

4. Quick Check:

   darken(color, percent) needs comma [OK]

Hint: Remember comma separates arguments in functions [OK]

Common Mistakes:

• Omitting comma between function arguments
• Using invalid color codes
• Removing % sign from percentage

5. You want to create a button with a base blue color #007BFF. On hover, the button should become 15% darker. Which Sass code correctly achieves this with variables and hover style?

hard

A. $btn-color: #007BFF;
.button {
background-color: $btn-color;
&:hover {
background-color: darken($btn-color, 15%);
}
}

B. $btn-color: #007BFF;
.button {
background-color: darken($btn-color, 15%);
&:hover {
background-color: $btn-color;
}
}

C. $btn-color: #007BFF;
.button {
background-color: lighten($btn-color, 15%);
&:hover {
background-color: darken($btn-color, 15%);
}
}

D. $btn-color: #007BFF;
.button {
background-color: $btn-color;
&:hover {
background-color: lighten($btn-color, 15%);
}
}

Solution

1. Step 1: Set base color variable

   The variable $btn-color is set to the base blue color #007BFF.

2. Step 2: Apply base color and darken on hover

   The button background uses $btn-color normally, and on hover uses darken($btn-color, 15%) to make it 15% darker.

3. Step 3: Verify hover effect logic

   $btn-color: #007BFF;
   .button {
     background-color: $btn-color;
     &:hover {
       background-color: darken($btn-color, 15%);
     }
   }

   correctly darkens on hover.

   $btn-color: #007BFF;
   .button {
     background-color: darken($btn-color, 15%);
     &:hover {
       background-color: $btn-color;
     }
   }

   reverses colors.

   $btn-color: #007BFF;
   .button {
     background-color: lighten($btn-color, 15%);
     &:hover {
       background-color: darken($btn-color, 15%);
     }
   }

   lightens base color incorrectly.

   $btn-color: #007BFF;
   .button {
     background-color: $btn-color;
     &:hover {
       background-color: lighten($btn-color, 15%);
     }
   }

   lightens on hover instead of darkening.

4. Final Answer:

   Code with base $btn-color and darken on hover -> Option A

5. Quick Check:

   Hover darken 15% =

   $btn-color: #007BFF;
   .button {
     background-color: $btn-color;
     &:hover {
       background-color: darken($btn-color, 15%);
     }
   }

   [OK]

Hint: Hover darker means darken() inside &:hover [OK]

Common Mistakes:

• Swapping lighten and darken functions
• Applying darken on base instead of hover
• Forgetting to use & for hover selector