*, *::after, *::before {
    box-sizing: border-box;
}

:root {
  font:1.2em/1.4 Arial, Helvetica, sans-serif;
  }

body {
  padding: 0 0 1em;
  max-width: 80rem;
  margin: 0;
}

header {
  background-color: #333;
  color: #fff;
  border: 5px solid #000;
}

header ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

header a {
  color: #fff;
  text-decoration: none;
  display: block;
  padding: 0.5em 1em;
  border-top: 1px solid #999;
}

header .title {
  font-size: 150%;
  font-style: italic;
  font-weight: bold;
  padding: 1em;
}

main {
  padding: 0 1em;
}

.cards {
  list-style: none;
  margin: 0;
  padding: 0;
}

.cards li {
  border: 5px solid #000;
  margin-bottom: 1em;
}

.cards h2 {
  background-color: #333;
  color: #fff;
  margin: 0;
  padding: 0.5em 1em;
}

.cards .inner {
  padding: 0.5em 1em;
}

.sidebar {
  background-color: #333;
  border: 5px solid #000;
  padding: 0.5em 1em;
  color: #fff;
  
  margin-block-start: .6em;
}


@media (min-width: 40em) {
  header {
    display: flex;
    justify-content: space-between;
    align-items: center;

    a {
      border-block-start: 0;
    }
  }

  header ul {
    display: flex;
  }

  main {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: .6em;
  }

  .cards {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: .6em;
  }
}