#chapter {
  margin-left: 5em;
  padding: 2.5rem 5rem;

  p {
    line-height: 1.75;
  }

  .image {
    margin: 3rem 0;
    text-align: center;

    img {
      border: 1px solid #eee;
      width: 95%;
    }

    .missing_image {
      background: red;
      color: white;
    }
  }
}

#section_listing {
  list-style-type: none;
  margin-left: -2rem;
  font-size: 90%;

  li {
    margin-bottom: 1rem;

    &.major {
      font-weight: bold;
    }
  }
}

.note_button {
  float: left;
  position: absolute;
  left: -6.5rem;
  font-size: 90%;
}

#chapter {
  margin-left: 5em;
  padding: 2.5rem 5rem;

  p {
    line-height: 1.75;
  }

  .image {
    margin: 3rem 0;
    text-align: center;

    img {
      border: 1px solid #eee;
      width: 95%;
    }

    .missing_image {
      background: red;
      color: white;
    }
  }

  .aside {
    background: #D9F1FF;
    padding: 1rem;
    margin-bottom: 2rem;
  }
}

#sidebar {
  padding-top: 5rem;
}

#section_listing {
  list-style-type: none;
  margin-left: -2rem;
  font-size: 90%;

  li {
    margin-bottom: 1rem;

    &.major {
      font-weight: bold;
    }
  }
}

.note_button {
  float: left;
  position: absolute;
  left: -6.5rem;
  font-size: 90%;
}

Add styling for asides, and padding for sidebars
Add styling for asides, and padding for sidebars
