Quick CSS Quiz #3

#challenge #css #quick #quiz

In this series, I try to focus on CSS weird parts, throw quiz and its answer, hoping to give a better understanding of how CSS works in depth.

The problem:

Having the following code snippet, for a paragraph element with font-size equals 12px, you want the paragraph's line-height to be equals to the double of its font-size(24px). Which of the following line-height values will achieve this if you apply it to the body element?
(note that the default font-size for browser is 16px)

<p style="font-size: 12px">Having fun solving CSS Quiz</p>

<style>
body {
  line-height: <value>;
}
</style>

Options:

200%
2em
2
double

The answer:

you can find the answer below, but please give yourself a couple of minutes to think about it, to make sure you benefit from this quiz.

👇👇👇

The correct answer is: "2" 🎉🎉
If you wonder why this is the correct answer, please read the discussions below, I will post the explanation soon.

Cover image original artwork by: Sergi Delgado

Top comments (9)

Mattia Astorino • Oct 6 '18 • Edited

This is very easy. A line-height with unitless value rappresent the ratio based on the element font-size computed value (or inherited) and allows children to compute their line-height based on their font-size.

Ps: same “quiz” here.
allthingssmitty.com/2017/01/30/nop...

Abdelrahman Ismail • Oct 6 '18 • Edited

It's very easy if you already know how line-height with unit-less value works 😉, but unfortunately most developers go with 2em.

And the original quiz posted by Kevin Yank here: 3 things (almost) no one knows css

Mattia Astorino • Oct 6 '18

Yes but unitless line height is just one of the accepted value. It’s not a “trick” like the previous quiz.

Abdelrahman Ismail • Oct 6 '18

To solve this quiz correctly, we should understand the line-height behavior with different values.

<length>:
The browser compute the line-height value for the current element, then nested child elements will inherit this fixed value form it.
For the first two options (which produce same results, gotcha!)
body line-height = 16 * 2 = 32px
p line-height = 32px inherited from body element

<number> (unitless):
Tells the browser to every nested element line-height value is this number multiplied by the element's own font size. In most cases, this is the preferred way to set line-height and avoid unexpected results due to inheritance.
For 2 option
body line-height = 16 * 2 = 32px
p line-height = 12 * 2 = 24px (which is the correct answer)

For more info:
line-height MDN
3 things (almost) no one knows css