FrontendTable-stakes
Box Model
Also written as CSS Box Model
The CSS rules for how an element's content, padding, border, and margin stack together to determine its actual size and spacing on the page.
Think of it like
Like a framed picture on a wall: the photo itself (content), the matting around it (padding), the frame (border), and the gap to the next picture (margin) — the box model is what all four add up to.
Junior or senior?
Junior sounds like
Gets tripped up by an element's size not matching expectations and can't explain why.
Senior sounds like
Can immediately diagnose it as a box-model/box-sizing issue and describe a real bug it caused.
Ask them
“Have you ever debugged a layout bug that turned out to be a box-model issue — box-sizing, unexpected padding or margin? What was it?”