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CSSmarkup~20 mins

Theme implementation basics in CSS - Practice Problems & Coding Challenges

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Challenge - 5 Problems
🎖️
Theme Master
Get all challenges correct to earn this badge!
Test your skills under time pressure!
🧠 Conceptual
intermediate
2:00remaining
What is the purpose of CSS custom properties in theme implementation?
CSS custom properties (variables) are often used in themes. What is their main benefit when creating a theme?
AThey allow changing colors and styles dynamically without rewriting all CSS rules.
BThey automatically generate new CSS classes for each theme color.
CThey replace the need for media queries in responsive design.
DThey prevent any CSS from being overridden by other styles.
Attempts:
2 left
💡 Hint
Think about how you can change a color in many places by changing just one value.
📝 Syntax
intermediate
2:00remaining
Which CSS snippet correctly defines a dark theme color variable?
You want to define a dark theme background color using a CSS custom property named --bg-color. Which snippet is correct?
A:root { --bg-color: #121212; }
Broot { bg-color: #121212; }
C:root { --bg-color #121212; }
D:root { bg-color: #121212; }
Attempts:
2 left
💡 Hint
Remember custom properties start with two dashes and are inside a selector.
❓ rendering
advanced
2:00remaining
What color will the background be when this CSS is applied?
Given the CSS below, what will be the background color of the element?
CSS
:root {
  --bg-color: white;
}

[data-theme="dark"] {
  --bg-color: black;
}

body {
  background-color: var(--bg-color);
}
ABlack always, because --bg-color is set to black in the dark theme.
BWhite if no data-theme attribute is set on <html> or <body>.
CTransparent, because var(--bg-color) is not defined.
DRed, because the default color is overridden by the browser.
Attempts:
2 left
💡 Hint
Think about which CSS rule applies when the data-theme attribute is missing.
❓ selector
advanced
2:00remaining
Which CSS selector applies styles only when dark theme is active?
You want to style all paragraphs with a light text color only when the dark theme is active using the data-theme attribute on . Which selector is correct?
Ahtml p[data-theme="dark"] { color: #eee; }
Bp[data-theme="dark"] { color: #eee; }
Chtml[data-theme="dark"] p { color: #eee; }
Dp.dark-theme { color: #eee; }
Attempts:
2 left
💡 Hint
The data-theme attribute is on the element, not on paragraphs.
❓ accessibility
expert
2:00remaining
How to ensure theme colors meet accessibility contrast standards?
When implementing a dark theme, what is the best way to ensure text colors meet accessibility contrast requirements?
AUse any dark background with light text without testing contrast.
BOnly rely on browser default colors for dark themes.
CUse the same colors as the light theme but invert them.
DUse a contrast checker tool to pick colors with sufficient contrast ratio.
Attempts:
2 left
💡 Hint
Accessibility means text must be easy to read against backgrounds.