/* Global variables. */
:root {
    /* Set sans-serif & mono fonts */
    --sans-font: -apple-system, BlinkMacSystemFont, "Avenir Next", Avenir,
      "Nimbus Sans L", Roboto, "Noto Sans", "Segoe UI", Arial, Helvetica,
      "Helvetica Neue", sans-serif;
    --mono-font: Consolas, Menlo, Monaco, "Andale Mono", "Ubuntu Mono", monospace;
    --standard-border-radius: 5px;
  
    /* Default (light) theme */
    --bg: #fff;
    --accent-bg: #f5f7ff;
    --text: #212121;
    --text-light: #585858;
    --border: #898EA4;
    --accent: #0d47a1;
    --code: #d81b60;
    --preformatted: #444;
    --marked: #ffdd33;
    --disabled: #efefef;
  }
  
  /* Dark theme */
  @media (prefers-color-scheme: dark) {
    :root {
      color-scheme: dark;
      --bg: #212121;
      --accent-bg: #2b2b2b;
      --text: #dcdcdc;
      --text-light: #ababab;
      --accent: #ffb300;
      --code: #f06292;
      --preformatted: #ccc;
      --disabled: #111;
    }
    /* Add a bit of transparency so light media isn't so glaring in dark mode */
    img,
    video {
      opacity: 0.8;
    }
  }
  
  /* Reset box-sizing */
  *, *::before, *::after {
    box-sizing: border-box;
  }
  
  /* Reset default appearance */
  textarea,
  select,
  input,
  progress {
    appearance: none;
    -webkit-appearance: none;
    -moz-appearance: none;
  }
  
  html {
    /* Set the font globally */
    font-family: var(--sans-font);
    scroll-behavior: smooth;
  }
  
  /* Make the body a nice central block */
  body {
    color: var(--text);
    background-color: var(--bg);
    font-size: 1.15rem;
    line-height: 1.5;
    display: grid;
    grid-template-columns: 1fr min(45rem, 90%) 1fr;
    margin: 0;
  }
  body > * {
    grid-column: 2;
  }
  
  /* Make the header bg full width, but the content inline with body */
  body > header {
    background-color: var(--accent-bg);
    border-bottom: 1px solid var(--border);
    text-align: center;
    padding: 0 0.5rem 2rem 0.5rem;
    grid-column: 1 / -1;
  }
  
  body > header h1 {
    max-width: 1200px;
    margin: 1rem auto;
  }
  
  body > header p {
    max-width: 40rem;
    margin: 1rem auto;
  }
  
  /* Add a little padding to ensure spacing is correct between content and header > nav */
  main {
    padding-top: 1.5rem;
  }
  
  body > footer {
    margin-top: 4rem;
    padding: 2rem 1rem 1.5rem 1rem;
    color: var(--text-light);
    font-size: 0.9rem;
    text-align: center;
    border-top: 1px solid var(--border);
  }
  
  /* Format headers */
  h1 {
    font-size: 3rem;
  }
  
  h2 {
    font-size: 2.6rem;
    margin-top: 3rem;
  }
  
  h3 {
    font-size: 2rem;
    margin-top: 3rem;
  }
  
  h4 {
    font-size: 1.44rem;
  }
  
  h5 {
    font-size: 1.15rem;
  }
  
  h6 {
    font-size: 0.96rem;
  }
  
  /* Prevent long strings from overflowing container */
  p, h1, h2, h3, h4, h5, h6 {
    overflow-wrap: break-word;
  }
  
  /* Fix line height when title wraps */
  h1,
  h2,
  h3 {
    line-height: 1.1;
  }
  
  /* Reduce header size on mobile */
  @media only screen and (max-width: 720px) {
    h1 {
      font-size: 2.5rem;
    }
  
    h2 {
      font-size: 2.1rem;
    }
  
    h3 {
      font-size: 1.75rem;
    }
  
    h4 {
      font-size: 1.25rem;
    }
  }
  
  /* Format links & buttons */
  a,
  a:visited {
    color: var(--accent);
  }
  
  a:hover {
    text-decoration: none;
  }
  
  button,
  [role="button"],
  input[type="submit"],
  input[type="reset"],
  input[type="button"],
  label[type="button"] {
    border: none;
    border-radius: var(--standard-border-radius);
    background-color: var(--accent);
    font-size: 1rem;
    color: var(--bg);
    padding: 0.7rem 0.9rem;
    margin: 0.5rem 0;
  }
  
  button[disabled],
  [role="button"][aria-disabled="true"],
  input[type="submit"][disabled],
  input[type="reset"][disabled],
  input[type="button"][disabled],
  input[type="checkbox"][disabled],
  input[type="radio"][disabled],
  select[disabled] {
    cursor: not-allowed;
  }
  
  input:disabled,
  textarea:disabled,
  select:disabled,
  button[disabled] {
    cursor: not-allowed;
    background-color: var(--disabled);
    color: var(--text-light)
  }
  
  input[type="range"] {
    padding: 0;
  }
  
  /* Set the cursor to '?' on an abbreviation and style the abbreviation to show that there is more information underneath */
  abbr[title] {
    cursor: help;
    text-decoration-line: underline;
    text-decoration-style: dotted;
  }
  
  button:enabled:hover,
  [role="button"]:not([aria-disabled="true"]):hover,
  input[type="submit"]:enabled:hover,
  input[type="reset"]:enabled:hover,
  input[type="button"]:enabled:hover,
  label[type="button"]:hover {
    filter: brightness(1.4);
    cursor: pointer;
  }
  
  button:focus-visible:where(:enabled, [role="button"]:not([aria-disabled="true"])),
  input:enabled:focus-visible:where(
    [type="submit"],
    [type="reset"],
    [type="button"]
  ) {
    outline: 2px solid var(--accent);
    outline-offset: 1px;
  }
  
  /* Format navigation */
  header > nav {
    font-size: 1rem;
    line-height: 2;
    padding: 1rem 0 0 0;
  }
  
  /* Use flexbox to allow items to wrap, as needed */
  header > nav ul,
  header > nav ol {
    align-content: space-around;
    align-items: center;
    display: flex;
    flex-direction: row;
    flex-wrap: wrap;
    justify-content: center;
    list-style-type: none;
    margin: 0;
    padding: 0;
  }
  
  /* List items are inline elements, make them behave more like blocks */
  header > nav ul li,
  header > nav ol li {
    display: inline-block;
  }
  
  header > nav a,
  header > nav a:visited {
    margin: 0 0.5rem 1rem 0.5rem;
    border: 1px solid var(--border);
    border-radius: var(--standard-border-radius);
    color: var(--text);
    display: inline-block;
    padding: 0.1rem 1rem;
    text-decoration: none;
  }
  
  header > nav a:hover {
    border-color: var(--accent);
    color: var(--accent);
    cursor: pointer;
  }
  
  /* Reduce nav side on mobile */
  @media only screen and (max-width: 720px) {
    header > nav a {
      border: none;
      padding: 0;
      text-decoration: underline;
      line-height: 1;
    }
  }
  
  /* Consolidate box styling */
  aside, details, pre, progress {
    background-color: var(--accent-bg);
    border: 1px solid var(--border);
    border-radius: var(--standard-border-radius);
    margin-bottom: 1rem;
  }
  
  aside {
    font-size: 1rem;
    width: 30%;
    padding: 0 15px;
    margin-left: 15px;
    float: right;
  }
  
  /* Make aside full-width on mobile */
  @media only screen and (max-width: 720px) {
    aside {
      width: 100%;
      float: none;
      margin-left: 0;
    }
  }
  
  article, fieldset {
    border: 1px solid var(--border);
    padding: 1rem;
    border-radius: var(--standard-border-radius);
    margin-bottom: 1rem;
  }
  
  article h2:first-child,
  section h2:first-child {
    margin-top: 1rem;
  }
  
  section {
    border-top: 1px solid var(--border);
    border-bottom: 1px solid var(--border);
    padding: 2rem 1rem;
    margin: 3rem 0;
  }
  
  /* Don't double separators when chaining sections */
  section + section,
  section:first-child {
    border-top: 0;
    padding-top: 0;
  }
  
  section:last-child {
    border-bottom: 0;
    padding-bottom: 0;
  }
  
  details {
    padding: 0.7rem 1rem;
  }
  
  summary {
    cursor: pointer;
    font-weight: bold;
    padding: 0.7rem 1rem;
    margin: -0.7rem -1rem;
    word-break: break-all;
  }
  
  details[open] > summary + * {
    margin-top: 0;
  }
  
  details[open] > summary {
    margin-bottom: 0.5rem;
  }
  
  details[open] > :last-child {
    margin-bottom: 0;
  }
  
  /* Format tables */
  table {
    border-collapse: collapse;
    display: block;
    margin: 1.5rem 0;
    overflow: auto;
    width: 100%;
  }
  
  td,
  th {
    border: 1px solid var(--border);
    text-align: left;
    padding: 0.5rem;
  }
  
  th {
    background-color: var(--accent-bg);
    font-weight: bold;
  }
  
  tr:nth-child(even) {
    /* Set every other cell slightly darker. Improves readability. */
    background-color: var(--accent-bg);
  }
  
  table caption {
    font-weight: bold;
    margin-bottom: 0.5rem;
  }
  
  /* Format forms */
  textarea,
  select,
  input {
    font-size: inherit;
    font-family: inherit;
    padding: 0.5rem;
    margin-bottom: 0.5rem;
    color: var(--text);
    background-color: var(--bg);
    border: 1px solid var(--border);
    border-radius: var(--standard-border-radius);
    box-shadow: none;
    max-width: 100%;
    display: inline-block;
  }
  label {
    display: block;
  }
  textarea:not([cols]) {
    width: 100%;
  }
  
  /* Add arrow to drop-down */
  select:not([multiple]) {
    background-image: linear-gradient(45deg, transparent 49%, var(--text) 51%),
      linear-gradient(135deg, var(--text) 51%, transparent 49%);
    background-position: calc(100% - 15px), calc(100% - 10px);
    background-size: 5px 5px, 5px 5px;
    background-repeat: no-repeat;
    padding-right: 25px;
  }
  
  /* checkbox and radio button style */
  input[type="checkbox"],
  input[type="radio"] {
    vertical-align: middle;
    position: relative;
    width: min-content;
  }
  
  input[type="checkbox"] + label,
  input[type="radio"] + label {
    display: inline-block;
  }
  
  input[type="radio"] {
    border-radius: 100%;
  }
  
  input[type="checkbox"]:checked,
  input[type="radio"]:checked {
    background-color: var(--accent);
  }
  
  input[type="checkbox"]:checked::after {
    /* Creates a rectangle with colored right and bottom borders which is rotated to look like a check mark */
    content: " ";
    width: 0.18em;
    height: 0.32em;
    border-radius: 0;
    position: absolute;
    top: 0.05em;
    left: 0.17em;
    background-color: transparent;
    border-right: solid var(--bg) 0.08em;
    border-bottom: solid var(--bg) 0.08em;
    font-size: 1.8em;
    transform: rotate(45deg);
  }
  input[type="radio"]:checked::after {
    /* creates a colored circle for the checked radio button  */
    content: " ";
    width: 0.25em;
    height: 0.25em;
    border-radius: 100%;
    position: absolute;
    top: 0.125em;
    background-color: var(--bg);
    left: 0.125em;
    font-size: 32px;
  }
  
  /* Makes input fields wider on smaller screens */
  @media only screen and (max-width: 720px) {
    textarea,
    select,
    input {
      width: 100%;
    }
  }
  
  /* Set a height for color input */
  input[type="color"] {
    height: 2.5rem;
    padding:  0.2rem;
  }
  
  /* do not show border around file selector button */
  input[type="file"] {
    border: 0;
  }
  
  /* Misc body elements */
  hr {
    border: none;
    height: 1px;
    background: var(--border);
    margin: 1rem auto;
  }
  
  mark {
    padding: 2px 5px;
    border-radius: var(--standard-border-radius);
    background-color: var(--marked);
  }
  
  img,
  video {
    max-width: 100%;
    height: auto;
    border-radius: var(--standard-border-radius);
  }
  
  figure {
    margin: 0;
    text-align: center;
  }
  
  figcaption {
    font-size: 0.9rem;
    color: var(--text-light);
    margin-bottom: 1rem;
  }
  
  blockquote {
    margin: 2rem 0 2rem 2rem;
    padding: 0.4rem 0.8rem;
    border-left: 0.35rem solid var(--accent);
    color: var(--text-light);
    font-style: italic;
  }
  
  cite {
    font-size: 0.9rem;
    color: var(--text-light);
    font-style: normal;
  }
  
  dt {
      color: var(--text-light);
  }
  
  /* Use mono font for code elements */
  code,
  pre,
  pre span,
  kbd,
  samp {
    font-family: var(--mono-font);
    color: var(--code);
  }
  
  kbd {
    color: var(--preformatted);
    border: 1px solid var(--preformatted);
    border-bottom: 3px solid var(--preformatted);
    border-radius: var(--standard-border-radius);
    padding: 0.1rem 0.4rem;
  }
  
  pre {
    padding: 1rem 1.4rem;
    max-width: 100%;
    overflow: auto;
    color: var(--preformatted);
  }
  
  /* Fix embedded code within pre */
  pre code {
    color: var(--preformatted);
    background: none;
    margin: 0;
    padding: 0;
  }
  
  /* Progress bars */
  /* Declarations are repeated because you */
  /* cannot combine vendor-specific selectors */
  progress {
    width: 100%;
  }
  
  progress:indeterminate {
    background-color: var(--accent-bg);
  }
  
  progress::-webkit-progress-bar {
    border-radius: var(--standard-border-radius);
    background-color: var(--accent-bg);
  }
  
  progress::-webkit-progress-value {
    border-radius: var(--standard-border-radius);
    background-color: var(--accent);
  }
  
  progress::-moz-progress-bar {
    border-radius: var(--standard-border-radius);
    background-color: var(--accent);
    transition-property: width;
    transition-duration: 0.3s;
  }
  
  progress:indeterminate::-moz-progress-bar {
    background-color: var(--accent-bg);
  }