Z-index stacking control in Tailwind - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the CSS property z-index control?

The z-index property controls the vertical stacking order of elements that overlap. Higher values appear on top of lower values.

beginner

How do you apply a z-index value of 10 using Tailwind CSS?

Use the class z-10 to set z-index: 10; in Tailwind CSS.

intermediate

What must be true about an element for z-index to work?

The element must have a position other than static (like relative, absolute, fixed, or sticky) for z-index to take effect.

beginner

What Tailwind class sets an element's position to <code>relative</code>?

The class relative sets position: relative; in Tailwind CSS.

intermediate

If two elements have the same z-index, which one appears on top?

The element that appears later in the HTML code (lower in the source order) will appear on top if z-index values are equal.

Which Tailwind class sets z-index: 20;?

A z-30

B z-10

C z-20

D z-5

The class z-20 sets z-index: 20; in Tailwind CSS.

What is required for z-index to work on an element?

A Element must have a position other than static

B Element must have a background color

C Element must be a block element

D Element must have a width set

z-index only works if the element's position is relative, absolute, fixed, or sticky, not static.

If two elements overlap and both have z-index: 10;, which one is on top?

A The one with position absolute

B The one that appears later in the HTML

C The one with a bigger width

D The one with a background color

When z-index values are equal, the element later in the HTML source appears on top.

Which Tailwind class sets position: relative;?

A relative

B pos-rel

C rel

D position-relative

The Tailwind class relative sets position: relative;.

What does a higher z-index value mean?

A Element has bigger size

B Element appears behind others

C Element is more transparent

D Element appears on top of others

Higher z-index values make elements appear on top of those with lower values.

Explain how z-index controls stacking order and what conditions must be met for it to work.

Think about how layers stack in real life, like papers on a desk.

Describe how to use Tailwind CSS classes to control stacking order and positioning of elements.

Remember Tailwind uses short class names for common CSS properties.

Practice

1. What does the z-index property control in Tailwind CSS?

easy

A. The size of an element

B. Which element appears on top when elements overlap

C. The color of an element

D. The font style of text

Solution

1. Step 1: Understand the purpose of z-index

   The z-index property controls stacking order of overlapping elements.

2. Step 2: Identify what z-index affects

   It determines which element appears on top visually when elements overlap.

3. Final Answer:

   Which element appears on top when elements overlap -> Option B

4. Quick Check:

   z-index controls stacking order = B [OK]

Hint: z-index means who is on top visually [OK]

Common Mistakes:

• Confusing z-index with size or color
• Thinking z-index changes element size
• Ignoring stacking order concept

2. Which Tailwind class correctly sets an element's z-index to 10?

easy

A. z-10

B. z-index-10

C. z10

D. index-z-10

Solution

1. Step 1: Recall Tailwind z-index syntax

   Tailwind uses z- prefix followed by the number to set z-index.

2. Step 2: Match correct class

   The correct class for z-index 10 is z-10.

3. Final Answer:

   z-10 -> Option A

4. Quick Check:

   Tailwind z-index class = A [OK]

Hint: Tailwind z-index classes start with 'z-' [OK]

Common Mistakes:

• Using 'z-index-10' which is invalid
• Missing dash between z and number
• Reversing order like 'index-z-10'

3. Given two overlapping divs with classes relative z-20 and relative z-10, which div appears on top?

medium

A. The div with z-20

B. They overlap with no order

C. They appear side by side

D. The div with z-10

Solution

1. Step 1: Understand z-index values

   Higher z-index values stack above lower ones.

2. Step 2: Compare given z-index values

   z-20 is higher than z-10, so it appears on top.

3. Final Answer:

   The div with z-20 -> Option A

4. Quick Check:

   Higher z-index on top = D [OK]

Hint: Higher z-index means on top visually [OK]

Common Mistakes:

• Assuming lower number is on top
• Ignoring position requirement
• Thinking they don't overlap

4. Why does the z-50 class not bring an element on top if it has no positioning class like relative or absolute?

medium

A. Because the element is hidden

B. Because z-50 is not a valid Tailwind class

C. Because z-index only works on positioned elements

D. Because z-index only works on text elements

Solution

1. Step 1: Recall z-index requirements

   z-index only affects elements with position set (relative, absolute, fixed, sticky).

2. Step 2: Analyze missing positioning

   Without positioning, z-index has no effect, so z-50 won't change stacking.

3. Final Answer:

   Because z-index only works on positioned elements -> Option C

4. Quick Check:

   Position required for z-index = A [OK]

Hint: z-index needs position set to work [OK]

Common Mistakes:

• Thinking z-50 is invalid
• Assuming z-index works without position
• Confusing visibility with stacking

5. You have three overlapping elements with classes absolute z-30, relative z-40, and fixed z-20. Which element will appear on top and why?

hard

A. The element with fixed z-20 because fixed position overrides z-index

B. The element with absolute z-30 because absolute is always on top

C. All elements appear at the same level because positions differ

D. The element with relative z-40 because it has the highest z-index

Solution

1. Step 1: Understand z-index and position interaction

   z-index controls stacking order only among positioned elements; all three are positioned.

2. Step 2: Compare z-index values

   The element with z-40 has the highest z-index, so it appears on top regardless of position type.

3. Final Answer:

   The element with relative z-40 because it has the highest z-index -> Option D

4. Quick Check:

   Highest z-index on positioned elements = C [OK]

Hint: Highest z-index wins if position is set [OK]

Common Mistakes:

• Thinking fixed is always on top
• Ignoring z-index values
• Assuming position type alone controls stacking