<!DOCTYPE html>
<html>
<head>
  <title>Chapter 1, using gaps</title>

  <style>
    /* Micro-resetting */
    body { padding: 0; margin: 0; }
    * { box-sizing: border-box; font-size: 25px; }

    /* Making things visible on the page */
    .container {
      border: 2px solid #555;
      padding: 8px;
      min-height: 100vh;
    }
    header {
      border: 2px solid #dd0808; /* Dark red */
      background-color: #ff6666; /* Light red */
    }
    aside {
      border: 2px solid #0ba7c6; /* Dark cyan */