* {
  margin: 0;
  padding: 0;
}

body {
  font-family: Georgia, serif;
  font-size: 16px;
  line-height: 1.5rem;
  color: #243b53;
  background: #fbfbfb;
  max-width: 64ch;
  margin: 1.5rem auto;
  padding: 1.5rem;
}

@media (min-width: 640px) {
  body {
    padding-left: 4.5rem;
  }
}

p,
pre,
ol,
ul,
h1,
h2,
h3 {
  margin: 1.5rem 0;
}

h1 {
  font-family: sans-serif;
  font-size: 2.25rem;
  font-weight: 700;
  letter-spacing: -0.025em;
  line-height: 3rem;
  color: #334e68;
  margin: 0;
}

@media (min-width: 640px) {
  body {
    margin: 6rem auto 3rem;
  }
}

body {
  counter-reset: chapter figures;
}

h1:before {
  counter-increment: chapter;
  content: counter(chapter) ". ";
}

@media (min-width: 640px) {
  h1:before {
    counter-increment: chapter;
    content: counter(chapter) ". ";
    float: left;
    margin-left: -3rem;
  }
}

h1 {
  counter-reset: section;
}

h2:before {
  counter-increment: section;
  content: counter(chapter) "." counter(section) ". ";
}

@media (min-width: 640px) {
  h2:before {
    float: left;
    margin-left: -3rem;
  }
}

h2 {
  font-family: sans-serif;
  font-weight: 300;
  font-size: 1.5rem;
  margin-top: 3rem;
  line-height: 2.25rem;
  color: #486581;
}

h3 {
  font-size: 1.125rem;
}

pre {
  background-color: #f0f4f8;
  padding: 0.75rem;
  margin-left: -0.75rem;
  margin-right: -0.75rem;
  white-space: pre-wrap;
  border: 1px solid #ddd;
}

ol {
  list-style-type: decimal;
}

code {
  font-size: 0.875em;
}

.note:before {
  content: "i";
  background-color: #486581;
  border-radius: 50%;
  display: inline-block;
  text-align: center;
  font-style: italic;
  margin-top: 0.25rem;
  color: #d9e2ec;
  display: block;
  width: 3rem;
  height: 3rem;
  font-size: 2rem;
  line-height: 3rem;
  margin-bottom: 1.5rem;
  margin-left: auto;
  margin-right: auto;
}

@media (min-width: 640px) {
  .note:before {
    font-size: 1rem;
    line-height: 1.25rem;
    width: 1.25rem;
    height: 1.25rem;
    float: left;
    margin-left: -2.25rem;
  }
}

.note {
  background-color: #d9e2ec;
  /* background-image: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 20 20"><path d="M2.93 17.07A10 10 0 1 1 17.07 2.93 10 10 0 0 1 2.93 17.07zm12.73-1.41A8 8 0 1 0 4.34 4.34a8 8 0 0 0 11.32 11.32zM9 11V9h2v6H9v-4zm0-6h2v2H9V5z"/></svg>');
  background-repeat: no-repeat;
  background-size: 1.5rem 1.5rem;
  background-position: 0.75rem 0.75rem; */
  color: #486581;
  padding: 0.75rem;
  margin-left: -0.75rem;
  margin-right: -0.75rem;
}

@media (min-width: 640px) {
  .note {
    padding-left: 3rem;
    margin-left: -3rem;
  }
}

h1:first-child {
  font-size: 4rem;
  line-height: 4rem;
  font-weight: 900;
  margin-top: 12rem;
  color: #102a43;
}

h1:first-child:before {
  content: none;
}

h1:first-child + p {
  font-size: 1.875rem;
  font-family: sans-serif;
  font-weight: 300;
  line-height: 3rem;
  margin-bottom: 3rem;
  color: #334e68;
}

h1:first-child + p + p {
  font-family: sans-serif;
  font-weight: 300;
  color: #829ab1;
  font-size: 1.25rem;
}

img {
  max-width: 100%;
}

p img {
  float: left;
  margin-right: 1.5rem;
  margin-bottom: 1.5rem;
}

video {
  width: 100%;
  -o-object-fit: scale-down;
     object-fit: scale-down;
}

a {
  color: #4d3df7;
  text-decoration: underline;
}

a:visited {
  color: #486581;
}

a:focus,
a:hover {
  color: #7069fa;
}

a:active {
  color: #a2a5fc;
}

table {
  border-top: 2px solid #d9e2ec;
  border-bottom: 2px solid #d9e2ec;
  margin-left: -0.75rem;
  margin-right: -0.75rem;
  border-collapse: collapse;
}

th {
  font-weight: bold;
  border-bottom: 2px solid #d9e2ec;
}

th,
td {
  padding: 0.25rem 0.75rem;
}

tr + tr td {
  border-top: 1px solid #d9e2ec;
}

blockquote {
  margin: 1.5em;
  color: #666;
}

strong,
dfn {
  font-weight: bold;
}

em,
dfn {
  font-style: italic;
}

del {
  color: #666;
}

li ul,
li ol {
  margin: 0;
}

ul {
  list-style-type: disc;
}

ol {
  list-style-type: decimal;
}

figure {
  max-width: 100%;
  margin-left: auto;
  margin-right: auto;
}

figure img {
  border: 1px solid #829ab1;
}

figcaption:before {
  counter-increment: figures;
  content: "Figure " counter(figures) ": ";
}

figcaption {
  font-size: 0.75rem;
  margin-top: 0.75rem;
  font-family: sans-serif;
  color: #829ab1;
}

hr {
  border: 0px;
  border-top: 1px solid #ddd;
  border-bottom: 1px solid #fff;
  margin-top: 4em;
  margin-bottom: 2em;
}

/* Code Highlighting */

.syntax-all {
}

.syntax-entity {
  color: #6f42c1;
}

.syntax-tag {
  color: #22863a;
}

.syntax-keyword {
  color: #d73a49;
}

.syntax-parameter {
  color: #24292e;
}

.syntax-string {
  color: #003878;
}

.syntax-constant {
  color: #005cc5;
}

.syntax-variable {
  color: #e36209;
}

.syntax-escape {
  font-weight: bold;
  color: #22863a;
}

.syntax-comment {
  color: #6a737d;
}

.syntax-error {
  color: #b31d28;
}

/* Markup Highlighting */

.syntax-heading {
  font-weight: bold;
  color: #005cc5;
}

.syntax-italic {
  font-style: italic;
  color: #24292e;
}

.syntax-bold {
  font-weight: bold;
  color: #24292e;
}

.syntax-deleted {
  color: #b31d28;
  background-color: #ffeef0;
}

.syntax-inserted {
  color: #22863a;
  background-color: #f0fff4;
}

.syntax-changed {
  color: #e36209;
  background-color: #ffebda;
}

.syntax-link {
  text-decoration: underline;
  color: #032f62;
}

.syntax-list {
  color: #e36209;
}

@keyframes highfade {
  0% {
    background-color: none;
  }

  20% {
    background-color: yellow;
  }

  100% {
    background-color: none;
  }
}

@-webkit-keyframes highfade {
  0% {
    background-color: none;
  }

  20% {
    background-color: yellow;
  }

  100% {
    background-color: none;
  }
}

a:target,
ol#footnotes li:target,
sup a:target {
  animation-name: highfade;
  animation-duration: 2s;
  animation-iteration-count: 1;
  animation-timing-function: ease-in-out;
  -webkit-animation-name: highfade;
  -webkit-animation-duration: 2s;
  -webkit-animation-iteration-count: 1;
  -webkit-animation-timing-function: ease-in-out;
}

a:target {
  border: 0;
  outline: 0;
}

.preview {
  border: 1px solid #ddd;
  border-top: 0;
  margin-left: -0.75rem;
  margin-right: -0.75rem;
  margin-top: -1.5rem;
  width: calc(100% + 1.425rem);
  height: auto;
}

.preview p {
  margin: 0;
}

.preview p + p {
  margin-top: 1.5rem;
}