A largura do contêiner <div> definida no fragmento CSS...

Include padding and border in the element's total width and height:

#example1 {
    box-sizing: border-box;
}

https://www.w3schools.com/CSSref/css3_pr_box-sizing.asp

Gabarito: d)

Gabarito: D

The box-sizing Property defines how the width and height of an element are calculated: should they include padding and borders, or not.

• box-sizing: content-box (default): Width and height only apply to the content of the element
• box-sizing: border-box: Width and height apply to all parts of the element: content, padding and borders

Fonte: https://www.w3schools.com/CSSref/tryit.asp?filename=trycss3_box-sizing

The box-sizing property allows us to include the padding and border in an element's total width and height.

If you set box-sizing: border-box; on an element, padding and border are included in the width and height

https://www.w3schools.com/css/css3_box-sizing.asp