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CSS CSS Basics (2014) Understanding Values and Units Em and Rem Units

John Conlin
John Conlin
3,801 Points
Posted by John Conlin
John Conlin
3,801 Points

Calculating an em size question.

The challenge task states: “Create a new rule that targets the h2. The h2's parent element has a font-size value of 16px. Use an em unit to give the h2 a font-size value equivalent to 53px.” If I apply the formula (em = desired element pixel value / parent element font-size in pixels) I calculate 53px / 16px (the parent element size) to get 3.313. This answer is stated as wrong. Is the parent of H2 actually the Header size of 1.8em (or 1.8rem)? Help on understanding this is appreciated!

style.css 
/* Complete the challenge by writing CSS below */

header {
  font-size: 1.8em;
}

.title {
  font-size: 1.625rem;
}

h1 {
  font-size: 5.625rem;
}
h2 {
  font-size: 3.313rem;
}
index.html 
<!DOCTYPE html>
<html>
  <head>
    <title>Lake Tahoe</title>
    <link rel="stylesheet" href="page.css">
    <link rel="stylesheet" href="style.css">
  </head>
  <body>
    <header>
      <span class="title">Journey through the Sierra Nevada Mountains</span>
      <h1>Lake Tahoe, California</h1>
    </header>
    <div class="main-content">
      <p>
        Lake Tahoe is one of the most breathtaking attractions located in California. It's home to a number of ski resorts, summer outdoor recreation, and tourist attractions. Snow and skiing are a significant part of the area's reputation.
      </p>
      <a href="#">Find out more</a>
      <h2>Check out all the Wildlife</h2>
      <p>
        As spawning season approaches, the fish acquire a humpback and protuberant jaw. After spawning, they die and their carcasses provide a feast for gatherings of mink, bears, and Bald eagles.
      </p>
      <a href="#">See the Wildlife</a>
      <h3>From Tents to Resorts</h3>
      <p>
        Lake Tahoe is full of wonderful places to stay. You have the ability to sleep in the outdoors in a tent, or relax like a king at a five star resort. Here are our top three resorts:
      </p>
    </div>
    <footer>
      <p>All rights reserved to the state of <a href="#">California</a>.</p>
      <a href="#top">Back to top &raquo;</a>
    </footer>
  </body>
</html>

1 Answer

Jason Anders
MOD
Jason Anders
Treehouse Moderator 145,860 Points
Jason Anders
Jason Anders
Treehouse Moderator 145,860 Points

Hey John,

You've pretty much got it, except for 2 things:

  1. Task 2 specifically asks for an em unit for the h2, but you are using rem.
  2. CSS values like to be very specific (as are the challenges). If you divide 53 by 16 you get 3.3125, but you entered 3.313. In CSS it is never a good idea to round the values. I've seen (and used) values with upwards of 8 or more decimal places.

So, if you just fix those two things up... you're good to go. :)

:dizzy:

John Conlin
John Conlin
3,801 Points
John Conlin
John Conlin
3,801 Points

Thanks for your fast reply to my question Jason. I redid the challenge and completed it. My calculator rounded up, and you have explained why the rounded value didn't work. Thanks again and have a great day!