Which property is used to control the scrolling of an image in the background?
Interviewer Expectations for this Question
01
Core Competency
Assesses fundamental understanding of HTML & CSS conventions, runtime behavior, and memory/performance considerations.
02
Evaluation Criteria
Hiring managers look for precision, avoidance of ambiguous jargon, and ability to explain trade-offs under real production conditions.
Comprehensive Model Answer
Verified Solution
The background-attachment property controls whether a background image scrolls along with the enclosing page content or remains fixed in a viewport position:
### Primary Values:
scroll(Default): The background image is fixed relative to the element itself and scrolls with the main page.fixed: The background image is pinned relative to the browser viewport, creating a smooth parallax scrolling effect as content moves over it:
.hero-banner {
background-image: url('/images/pattern.svg');
background-attachment: fixed;
background-position: center;
background-size: cover;
}
local: The background image scrolls with the element's internal scrollable contents.
Candidate Response Strategy & Interview Tips
- Start with a concise one-sentence summary: Deliver a direct, confident answer first before expanding into nuances.
- Demonstrate real-world trade-offs: Discuss where this approach excels and when you would avoid it in production systems.
- Discuss complexity & edge cases: Proactively explain time/space complexity or boundary conditions (null values, scale limits).
- Prepare for interviewer follow-ups: Technical hiring panels frequently probe deeper into concurrency, backward compatibility, or alternative libraries.