What is CSS cascade - Practice Questions & Exercises

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding CSS Cascade Priority

Which CSS rule will apply to the paragraph below if these styles are all present?

p { color: blue; }
.highlight { color: red; }
#main { color: green; }

HTML:
<p id="main" class="highlight">Hello</p>

A The paragraph text will be black (default).

B The paragraph text will be red.

C The paragraph text will be green.

D The paragraph text will be blue.

💡 Hint

Remember that IDs have higher priority than classes and element selectors in CSS cascade.

CSS cascade decides which style applies when multiple rules target the same element. ID selectors (#main) have higher priority than class selectors (.highlight) and element selectors (p). So, the color green from #main wins.

📝 Syntax

intermediate

Which CSS rule overrides others due to !important?

Given these CSS rules:

div { color: blue !important; }
.alert { color: red; }

What color will a <div class="alert"> show?

A Red, because class selectors override element selectors.

B It will cause a syntax error.

C Black, because no color applies.

D Blue, because !important overrides normal declarations.

💡 Hint

The !important keyword gives a rule the highest priority.

The !important declaration makes the blue color rule override the red color from the class selector, even though classes normally have higher specificity than elements.

❓ selector

advanced

Which selector has the highest specificity?

Consider these selectors:

A) ul li a:hover
B) #nav .menu a
C) .header .nav a.active
D) body.home ul li a

Which selector has the highest specificity according to CSS cascade rules?

A ul li a:hover

B #nav .menu a

C .header .nav a.active

D body.home ul li a

💡 Hint

ID selectors count more than classes and elements in specificity.

Selector B has an ID (#nav), which gives it higher specificity than selectors with only classes and elements.

❓ layout

advanced

How does CSS cascade affect conflicting layout styles?

If two CSS rules set different display values for the same element:

.box { display: flex; }
#container { display: grid; }

And the HTML is:
<div id="container" class="box">Content</div>

What will be the display style of the div?

A The div will use display: grid.

B The div will use display: flex.

C The div will have no display style and default to block.

D The div will cause a layout error.

💡 Hint

ID selectors have higher specificity than class selectors.

The ID selector (#container) has higher specificity than the class selector (.box), so display: grid applies.

❓ accessibility

expert

How does CSS cascade impact accessibility when styles conflict?

You have these CSS rules:

button { color: black; }
.disabled { color: gray !important; }
#submitBtn { color: white; }

HTML:
<button id="submitBtn" class="disabled">Submit</button>

What color will the button text be, and why is this important for accessibility?

A Gray, because !important overrides ID selectors.

B White, because ID selectors override classes even with !important.

C Black, because element selectors have priority.

D The button will be invisible due to conflicting colors.

💡 Hint

The !important keyword overrides normal specificity rules.

The .disabled class uses !important, which overrides the ID selector color. This ensures the button looks disabled visually, which is important for users to understand its state.