Vendor prefix mixin patterns in SASS - Practice Problems & Coding Challenges

Challenge - 5 Problems

📝 Syntax

intermediate

What is the output CSS of this Sass mixin usage?

Given the following Sass mixin and usage, what CSS will be generated?

@mixin transform($value) {
  -webkit-transform: $value;
  -moz-transform: $value;
  transform: $value;
}

.box {
  @include transform(rotate(45deg));
}

SASS

@mixin transform($value) {
  -webkit-transform: $value;
  -moz-transform: $value;
  transform: $value;
}

.box {
  @include transform(rotate(45deg));
}

A

.box {
  -moz-transform: rotate(45deg);
  transform: rotate(45deg);
}

B

.box {
  transform: rotate(45deg);
  -webkit-transform: rotate(45deg);
  -moz-transform: rotate(45deg);
}

C

.box {
  -webkit-transform: rotate(45deg);
  transform: rotate(45deg);
}

D

.box {
  -webkit-transform: rotate(45deg);
  -moz-transform: rotate(45deg);
  transform: rotate(45deg);
}

💡 Hint

Remember the order of properties in the mixin matches the output order.

The mixin outputs the properties in the order written: -webkit-transform, then -moz-transform, then transform. The CSS output preserves this order.

🧠 Conceptual

intermediate

Why use vendor prefix mixins in Sass?

Which of the following best explains why developers use vendor prefix mixins in Sass?

A To write CSS properties once and automatically add all needed vendor prefixes for browser support.

B To avoid writing any CSS properties and rely on browsers to add prefixes automatically.

C To make CSS files larger by repeating properties with prefixes manually.

D To prevent browsers from applying any vendor-specific styles.

💡 Hint

Think about how mixins help with repetitive code.

Vendor prefix mixins let developers write a property once and generate all necessary prefixed versions, saving time and reducing errors.

❓ selector

advanced

Which selector is targeted by this Sass mixin usage?

Given this Sass code, which CSS selector will the styles apply to?

@mixin user-select($value) {
  -webkit-user-select: $value;
  -moz-user-select: $value;
  -ms-user-select: $value;
  user-select: $value;
}

button {
  @include user-select(none);
}

SASS

@mixin user-select($value) {
  -webkit-user-select: $value;
  -moz-user-select: $value;
  -ms-user-select: $value;
  user-select: $value;
}

button {
  @include user-select(none);
}

A Only <button> elements with class 'user-select'

B Only <button> elements inside a container with class 'user-select'

C All <button> elements on the page

D All elements with attribute user-select='none'

💡 Hint

Look at the selector before the mixin usage.

The styles apply to all

❓ layout

advanced

How does this vendor prefix mixin affect layout rendering?

Consider this Sass mixin and usage:

@mixin flex-center {
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  justify-content: center;
  align-items: center;
}

.container {
  @include flex-center;
  height: 200px;
}

What visual effect will the container have?

SASS

@mixin flex-center {
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  justify-content: center;
  align-items: center;
}

.container {
  @include flex-center;
  height: 200px;
}

A The container will center its child elements horizontally and vertically within 200px height.

B The container will stack child elements vertically without centering.

C The container will hide child elements due to conflicting display properties.

D The container will scroll child elements horizontally.

💡 Hint

Think about what flexbox centering does.

The mixin sets display to flex with vendor prefixes and centers children horizontally and vertically, so children appear centered inside the 200px tall container.

❓ accessibility

expert

Which vendor prefix mixin usage best supports accessibility for focus outlines?

Which Sass mixin usage ensures consistent focus outlines across browsers for accessibility?

@mixin focus-outline($color) {
  outline: 2px solid $color;
  outline-offset: 2px;
  -webkit-outline-offset: 2px;
}

Choose the correct usage:

SASS

@mixin focus-outline($color) {
  outline: 2px solid $color;
  outline-offset: 2px;
  -webkit-outline-offset: 2px;
}

input:focus {
  @include focus-outline(blue);
}

A input:focus { @include focus-outline(blue); }

B input:focus-visible { @include focus-outline(blue); }

C input { @include focus-outline(blue); }

D input:hover { @include focus-outline(blue); }

💡 Hint

Focus outlines should appear only when keyboard focusing, not on hover.

Using :focus-visible applies outlines only when the element is focused via keyboard or assistive technology, improving accessibility by avoiding outlines on mouse clicks.