Let's search for some other non-percentage-based widths/margins/paddings. So we're not worried about anything related to vertical distance, like height, margin-top, margin-bottom, padding-top or padding-bottom. And we're not worried about any value of 0.

We will come across auto for the left and right margin in the wrapper rule set:

.wrapper {
  max-width: 960px;
  width: 90%;
  margin: 0 auto;
}

This doesn't need to be converted into a percentage because auto automatically calculates the width based on the space available, so it's as good as a percentage.

We are worried about this margin property in the following declaration block:

.content-block .figure {
  float: left;
  margin: 30px;
  border: 15px solid #fff;
  overflow: hidden;
}

This rule set has a margin of 30px; it's using the single value syntax. This means the...