html, body {
  padding: 0;
  margin: 0;
  //font-family: Georgia,Times,Times New Roman,serif;
  font-family: Lucida Bright, Georgia, serif;
}

body {
  font-size: 20px;
  line-height: 1.6em;
}

* {
  box-sizing: border-box;
}

.book {
  margin-bottom: 50vh;
}

.cover {
  height: 100vh;
}

.cover img {
  max-width: 100%;
  height: 100%;
  object-fit: cover;
}

.cover + .chapter {
  margin-top: 3rem;
}

.container {
  max-width: 600px;
  margin: 0 auto;
}

.toc li {
  padding: .2em 0;
  font-weight: 600;
  font-family: Tahoma, Verdana, Segoe, sans-serif;

}

.toc a {
  color: inherit;
  padding: .2em 0;
}

.toc a:hover {
  text-decoration: none;
}

article {
  background-color: #ffffff;
  display: block;
}

.header {
  position: sticky;
  top: 0;
  background-color: #ffffff;
  display: block;
  width: 100%;
  padding: 0.5em 0;
}

article h1 {
  font-family: Tahoma, Verdana, Segoe, sans-serif;
  margin: 0;
  font-size: 1.5rem;
  padding: 0 1rem;
}

h1 a {
  color: inherit;
  text-decoration: none;
}

article p {
  padding-left: 1rem;
  padding-right: 1rem;
}

article p > img {
  width: calc(100% + 2rem);
  max-width: calc(100% + 2rem);
  margin-left: calc(-1 * 1rem);
}

hr {
  max-width: 50%;
  display: block;
  margin: 2em auto;
}

.chapter-title {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.chapter-title .back {
  font-size: 0.5em;
  padding: 0.25em 0;
  text-decoration: underline;
}

.chapter-title .back:hover {
  text-decoration: none;
}

@media (min-width: 1000px) {
  body {
    font-size: 18px;
  }

  article p > img {
    width: calc(100% + 12rem);
    max-width: calc(100% + 12rem);
    margin-left: calc(-1 * 2rem);
    margin-top: 1em;
    margin-bottom: 1em;
    box-shadow: 5px 5px 10px -5px #00000088;
  }

  hr {
    margin: 4em auto;
    max-width: 33%;
  }
}

#toc {
  margin-top: 3em;
}