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CSS CSS Foundations The Box Model Width, Height and Overflow Properties

Box Model Challenge: Question 3 Box-sizing property.

I'm stuck on the Box Model Challenge Question 3 pertaining to box-sizing. I don't think I understand how I'm supposed to answer the question.

<!DOCTYPE html>
    <title>Width, Height and Overflow Properties</title>
    <link rel="stylesheet" href="page.css">
    <link rel="stylesheet" href="style.css">
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/* Complete the challenge by writing CSS below */
a {
  display: inline-block;
  width: 100px;
.main {
  box-sizing: 40px;

1 Answer

Alex Heil
Alex Heil
53,534 Points

hey Kathryn Notson , by default the css boxmodel works by adding padding to an element. means if you have a div that's 400px wide and you add 20px padding it will expand to 440px total (400px element + 20px padding on the left + 20px padding on the right).

however we can change this behaviour by changing the boxmodel to something called border-box. when we do so then the width we give the element (400px in this case) is not expanded, the padding is getting substracted automatically and we don't have to worry about it. to use it we write it like this:

.main {
box-sizing: border-box;

if you add this to your challenge it should pass just fine. hope that helps and have a nice day ;)

Believe it or not, I did figure it out myself! Thanks anyway. The explanation helps.

I'm having a connection issue with the server @ SE Works, so I've had to restart this challenge several times this afternoon before completely it successfully.