Flex basis and sizing in Tailwind - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does flex-basis control in a flex container?

flex-basis sets the initial main size of a flex item before free space is distributed. It defines the starting width or height depending on flex direction.

beginner

How do you set flex-basis to 50% using Tailwind CSS?

Use the class basis-1/2 to set flex-basis to 50% of the parent's size.

intermediate

What is the difference between flex-grow and flex-basis?

flex-basis sets the starting size of a flex item.
flex-grow controls how much the item can grow to fill extra space.

beginner

Which Tailwind class sets <code>flex-basis</code> to <code>auto</code>?

The class basis-auto sets flex-basis to auto, meaning the item sizes based on its content.

intermediate

If you want a flex item to never shrink smaller than 100px, which Tailwind class helps with sizing?

Use min-w-[100px] to set a minimum width of 100 pixels, preventing the item from shrinking below that size.

Which Tailwind class sets flex-basis to 25%?

A basis-1/4

B basis-1/2

C basis-1/3

D basis-auto

basis-1/4 sets flex-basis to 25% (one quarter) of the container size.

What does basis-auto do in Tailwind CSS?

A Sets flex-basis to auto, sizing by content

B Sets flex-basis to 0

C Sets flex-grow to 1

D Sets flex-shrink to 0

basis-auto means the flex item sizes itself based on its content.

If a flex item has basis-1/2 and grow, what happens when extra space is available?

A It stays at 50% width

B It shrinks below 50%

C It grows larger than 50%

D It disappears

basis-1/2 sets initial size to 50%, and grow allows it to expand beyond that if space is free.

Which property controls the minimum size a flex item can shrink to?

A flex-basis

B min-width or min-height

C flex-grow

D flex-shrink

Minimum size is controlled by min-width or min-height, which can be set in Tailwind with classes like min-w-[value].

What is the default value of flex-basis if not set?

A 0

B 100%

C none

D auto

The default flex-basis is auto, meaning the item sizes based on its content or width/height.

Explain how flex-basis works in a flex container and how Tailwind CSS helps set it.

Think about the starting size of a flex item before it grows or shrinks.

Describe how you can control the minimum size of a flex item using Tailwind CSS.

Minimum size is not flex-basis but a separate CSS property.

Practice

1. What does the Tailwind class basis-1/3 do in a flex container?

easy

A. Makes the flex item grow to fill one-third of the container

B. Sets the initial size of the flex item to one-third of the container's main size

C. Prevents the flex item from shrinking below one-third of its size

D. Sets the flex item to always be exactly one-third of the container width regardless of content

Solution

1. Step 1: Understand flex basis meaning

   Flex basis sets the starting size of a flex item before growing or shrinking.

2. Step 2: Interpret basis-1/3 in Tailwind

   This class sets the flex basis to one-third of the container's main size, not forcing exact size but initial size.

3. Final Answer:

   Sets the initial size of the flex item to one-third of the container's main size -> Option B

4. Quick Check:

   Flex basis = initial size = one-third [OK]

Hint: Flex basis sets start size, not final size [OK]

Common Mistakes:

• Confusing basis with grow or shrink
• Thinking basis fixes size exactly
• Assuming basis prevents shrinking

2. Which of the following is the correct Tailwind class to set a flex item's basis to 16rem?

easy

A. basis-16rem

B. basis-64rem

C. basis-16

D. basis-64

Solution

1. Step 1: Recall Tailwind sizing scale

   Tailwind uses numeric scale where 64 equals 16rem (4rem * 16).

2. Step 2: Match class syntax

   The correct class is basis-64 to set basis to 16rem, no 'rem' suffix used.

3. Final Answer:

   basis-64 -> Option D

4. Quick Check:

   basis-64 = 16rem in Tailwind [OK]

Hint: Tailwind uses numbers, not units, for spacing [OK]

Common Mistakes:

• Adding 'rem' suffix in class name
• Using wrong numeric scale
• Confusing basis with width classes

3. Given this HTML snippet:

<div class="flex w-96">
  <div class="basis-1/4 bg-blue-500">Box 1</div>
  <div class="basis-1/2 bg-red-500">Box 2</div>
  <div class="basis-1/4 bg-green-500">Box 3</div>
</div>

What will be the width of Box 2 inside the 24rem wide container?

medium

A. 6rem

B. 24rem

C. 12rem

D. 18rem

Solution

1. Step 1: Calculate container width in rem

   The container width is 24rem (w-96 means 24rem).

2. Step 2: Calculate Box 2 basis size

   Box 2 has basis-1/2, so initial size is half of 24rem = 12rem.

3. Final Answer:

   12rem -> Option C

4. Quick Check:

   Half of 24rem = 12rem [OK]

Hint: Multiply container width by basis fraction [OK]

Common Mistakes:

• Confusing basis fraction with grow factor
• Using container width in px instead of rem
• Adding basis sizes instead of calculating individually

4. You wrote this Tailwind code:

<div class="flex">
  <div class="basis-2/3">Item 1</div>
  <div class="basis-1/2">Item 2</div>
</div>

But the items overflow the container width. What is the main reason?

medium

A. The sum of basis sizes (2/3 + 1/2) exceeds 1, causing overflow

B. Missing flex-grow classes to allow shrinking

C. Tailwind does not support fractional basis classes

D. The container needs flex-wrap to prevent overflow

Solution

1. Step 1: Calculate the sum of basis fractions

   2/3 + 1/2 = 4/6 + 3/6 = 7/6 > 1.

2. Step 2: Understand the effect

   When the sum of flex-basis values exceeds 1, it causes the flex items to overflow the container.

3. Final Answer:

   The sum of basis sizes (2/3 + 1/2) exceeds 1, causing overflow -> Option A

4. Quick Check:

   Sum of basis fractions > 1 causes overflow [OK]

Hint: Check if basis fractions sum over 1 for overflow [OK]

Common Mistakes:

• Assuming basis fractions always fit container
• Ignoring default flex shrink behavior
• Confusing grow with shrink effects

5. You want three flex items inside a container to have these widths initially: 25%, 50%, and 25%. You also want the middle item to grow twice as fast as the others when space is available. Which Tailwind classes correctly achieve this?

hard

A. basis-1/4 grow, basis-1/2 [flex-grow:2], basis-1/4 grow

B. basis-1/4 flex-grow-1, basis-1/2 flex-grow-2, basis-1/4 flex-grow-1

C. basis-1/4 grow, basis-1/2 grow [flex-grow:2], basis-1/4 grow

D. basis-1/4 grow, basis-1/2 grow, basis-1/4 grow

Solution

1. Step 1: Set correct basis classes

   Use basis-1/4 for 25% and basis-1/2 for 50% widths.

2. Step 2: Apply grow classes

   Tailwind uses grow for flex-grow:1 and [flex-grow:2] for flex-grow:2.

3. Step 3: Assign grow classes to items

   First and third items get grow, middle item gets [flex-grow:2] to grow twice as fast.

4. Final Answer:

   basis-1/4 grow, basis-1/2 [flex-grow:2], basis-1/4 grow -> Option A

5. Quick Check:

   Use grow and [flex-grow:2] with basis fractions [OK]

Hint: Use grow and [flex-grow:2] classes for different grow rates [OK]

Common Mistakes:

• Using non-existent flex-grow-1 class
• Combining grow and grow-2 on same element
• Forgetting to set basis sizes