<!doctype html>
<html lang="en">
  <head>
    <meta charset="utf-8" />
    <title>Sizing: percentage margins and padding</title>
    <link rel="stylesheet" href="../styles.css" />
    <style>
      * {
        box-sizing: border-box;
      }
    </style>

    <style class="editable">
      .box {
        border: 5px solid darkblue;
        width: 300px;
        margin: 10%;
        padding: 10%;
      }
    </style>
  </head>

  <body>
    <section class="preview">
      <div class="box">I have margin and p