Combining & with BEM naming in SASS - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ selector

intermediate

What CSS selector does this Sass code produce?

Given the Sass code below, what is the final CSS selector generated for the .block__element--modifier style?

SASS

.block {
  &__element {
    &--modifier {
      color: red;
    }
  }
}

A .block__element--modifier { color: blue; }

B .block .__element--modifier { color: red; }

C .block__element .--modifier { color: red; }

D .block__element--modifier { color: red; }

💡 Hint

Remember that & replaces the parent selector exactly where it appears.

The & symbol in Sass replaces the parent selector. Here, &__element becomes .block__element, and then &--modifier becomes .block__element--modifier.

📝 Syntax

intermediate

Which option causes a syntax error in Sass when combining & with BEM naming?

Identify which Sass snippet below will cause a syntax error due to incorrect use of & with BEM naming.

A

.block {
  &--modifier
    color: green;
  }

B

.block {
  &__element--modifier {
    color: red;
  }
}

C

.block {
  &__element {
    color: blue;
  }
}

D

.block {
  &__element--modifier {
    &--extra {
      color: yellow;
    }
  }
}

💡 Hint

Check for missing opening braces `{` after nested selectors.

Option A is missing the opening curly brace `{` after `&--modifier`, causing a Sass syntax error. Sass expects `{` immediately after a selector.

❓ selector

intermediate

Which Sass code produces a descendant selector instead of BEM concatenated class?

Choose the Sass code that compiles to a descendant selector `.block __element` instead of the proper BEM concatenated `.block__element`.

A

.block {
  & __element {
    color: yellow;
  }
}

B

.block {
  &--modifier {
    color: green;
  }
}

C

.block {
  &__element {
    color: blue;
  }
}

D

.block {
  &__element--modifier {
    color: red;
  }
}

💡 Hint

A space after & inserts a descendant combinator (space), preventing concatenation for BEM class names.

Option A has a space between & and __element, so & is replaced by .block, resulting in `.block __element` (descendant selector) instead of `.block__element` (single BEM class).

❓ rendering

advanced

What color will the element with class block__element--modifier have?

Given the Sass code below, what color will the element with class block__element--modifier display in the browser?

SASS

.block {
  &__element {
    color: blue;
    &--modifier {
      color: red;
    }
  }
}

A Blue

B No color applied

C Red

D Purple

💡 Hint

Look at the nested selectors and which color applies to the modifier class.

The .block__element sets color blue, but .block__element--modifier overrides it with color red, so the element with that class will be red.

❓ accessibility

expert

How to improve accessibility when using BEM modifiers with & in Sass?

You have a button styled with BEM naming and Sass using & for modifiers. Which practice improves accessibility the most?

A Use only BEM modifiers with & in Sass to change colors for visual states.

B Add ARIA roles and states to the button element in HTML, not just rely on CSS classes.

C Add tabindex="-1" to all modifier classes to prevent keyboard focus.

D Use !important in Sass modifiers to ensure styles override defaults.

💡 Hint

Think about what helps screen readers and keyboard users, not just visual styles.

Accessibility requires semantic HTML and ARIA attributes to communicate state and roles to assistive tech. CSS alone cannot provide this.

Practice

1. What does the & symbol represent when used in Sass with BEM naming?

easy

A. It resets all styles inside the block.

B. It creates a new CSS class unrelated to the parent.

C. It imports external CSS files.

D. It refers to the current parent selector in the nested block.

Solution

1. Step 1: Understand the role of & in Sass

   The & symbol in Sass means "use the current parent selector" inside nested rules.

2. Step 2: Connect with BEM naming

   When combined with BEM, &__element or &--modifier appends to the parent block's class name.

3. Final Answer:

   It refers to the current parent selector in the nested block. -> Option D

4. Quick Check:

   & = current parent selector [OK]

Hint: Remember & means "this block" in nested Sass [OK]

Common Mistakes:

• Thinking & creates a new unrelated class
• Confusing & with a CSS variable
• Using & to import files

2. Which of the following Sass snippets correctly uses & to create a BEM modifier for a block named .card?

easy

A. &__active { background: green; }

B. .card--active { background: green; }

C. &--active { background: green; }

D. &-active { background: green; }

Solution

1. Step 1: Identify BEM modifier syntax

   Modifiers use double dashes: --modifier, so &--active appends --active to the parent block.

2. Step 2: Check other options

   .card--active { background: green; } repeats the full class, not using &. &__active { background: green; } uses __ which is for elements, not modifiers. &-active { background: green; } uses a single dash, which is incorrect for BEM modifiers.

3. Final Answer:

   &--active { background: green; } -> Option C

4. Quick Check:

   Modifier = &--modifier [OK]

Hint: Use &--modifier for modifiers inside blocks [OK]

Common Mistakes:

• Using single dash instead of double dash for modifiers
• Confusing elements (__element) with modifiers (--modifier)
• Writing full class name instead of using &

3. Given the Sass code below, what CSS will it generate?

.button {
  color: blue;
  &__icon {
    margin-right: 0.5rem;
  }
  &--large {
    font-size: 2rem;
  }
}

medium

A. .button { color: blue; } &__icon { margin-right: 0.5rem; } &--large { font-size: 2rem; }

B. .button { color: blue; } .button__icon { margin-right: 0.5rem; } .button--large { font-size: 2rem; }

C. .button { color: blue; } .icon { margin-right: 0.5rem; } .large { font-size: 2rem; }

D. .button { color: blue; } .button_icon { margin-right: 0.5rem; } .button_large { font-size: 2rem; }

Solution

1. Step 1: Understand & usage in nested selectors

   The & appends to the parent selector .button. So &__icon becomes .button__icon and &--large becomes .button--large.

2. Step 2: Write the generated CSS

   The CSS will have three selectors: .button, .button__icon, and .button--large with their respective styles.

3. Final Answer:

   .button { color: blue; } .button__icon { margin-right: 0.5rem; } .button--large { font-size: 2rem; } -> Option B

4. Quick Check:

   & + BEM = combined class names [OK]

Hint: &__element and &--modifier append to block class [OK]

Common Mistakes:

• Using underscore instead of double underscore for elements
• Not combining & with parent selector
• Leaving & in final CSS

4. Identify the error in this Sass code using BEM naming:

.menu {
  &__item {
    color: black;
  }
  &-active {
    font-weight: bold;
  }
}

medium

A. The modifier should use double dashes: &--active instead of &-active.

B. The element selector &__item is invalid and should be &-item.

C. The parent selector .menu is missing a dot.

D. The color property cannot be inside &__item.

Solution

1. Step 1: Check BEM modifier syntax

   Modifiers in BEM use double dashes --, so &-active is incorrect; it should be &--active.

2. Step 2: Verify element syntax

   &__item is correct for elements, so no error there.

3. Final Answer:

   The modifier should use double dashes: &--active instead of &-active. -> Option A

4. Quick Check:

   Modifier syntax = &--modifier [OK]

Hint: Modifiers always use double dashes -- not single [OK]

Common Mistakes:

• Using single dash for modifiers
• Confusing element and modifier syntax
• Thinking &__item is invalid

5. You want to style a BEM block .profile with an element avatar and a modifier highlighted. Which Sass code correctly combines & with BEM naming to style both the element and modifier inside .profile?

hard

A. .profile {
&__avatar {
border-radius: 50%;
}
&--highlighted {
background-color: yellow;
}
}

B. .profile {
&-avatar {
border-radius: 50%;
}
&-highlighted {
background-color: yellow;
}
}

C. .profile {
&__avatar {
border-radius: 50%;
}
&-highlighted {
background-color: yellow;
}
}

D. .profile {
&-avatar {
border-radius: 50%;
}
&--highlighted {
background-color: yellow;
}
}

Solution

1. Step 1: Apply BEM element syntax

   Elements use double underscore __, so &__avatar correctly targets .profile__avatar.

2. Step 2: Apply BEM modifier syntax

   Modifiers use double dash --, so &--highlighted correctly targets .profile--highlighted.

3. Step 3: Check other options

   Options A, C, and D use single dash for either element or modifier, which is incorrect in BEM.

4. Final Answer:

   .profile { &__avatar { border-radius: 50%; } &--highlighted { background-color: yellow; } } -> Option A

5. Quick Check:

   Element = &__element, Modifier = &--modifier [OK]

Hint: Use &__element and &--modifier exactly for BEM [OK]

Common Mistakes:

• Using single dash for elements or modifiers
• Mixing element and modifier syntax
• Not nesting inside the block selector