devdocs/assets/stylesheets/global/_base.scss

html {
  height: 100%;
  font-size: 100%;
  background: #fff; // fallback to show the error message to browsers that don't support CSS variables.
  background: var(--documentBackground);

  @include mobile { font-size: 93.75%; }

  @include print { background: none; }
  @import 'global/print';
}

html._theme-default {
  color-scheme: light only;
}
html._theme-dark {
  color-scheme: dark only;
}

body {
  height: 100%;
  margin: 0;
  overflow: auto;
  font-size: 1em;
  font-weight: normal;
  font-family: $baseFont;
  line-height: 1.7;
  color: $textColor; // fallback to show the error message to browsers that don't support CSS variables.
  color: var(--textColor);
  word-wrap: break-word;
  overflow-wrap: break-word;
  background: var(--contentBackground);
  touch-action: manipulation;
  -webkit-tap-highlight-color: rgba(black, 0);
  -webkit-touch-callout: none;
  -webkit-text-size-adjust: 100%;
      -ms-text-size-adjust: 100%;
}

a {
  color: var(--linkColor);
  text-decoration: var(--linkTextDecoration);

  &:hover {
    color: var(--linkColorHover);
    text-decoration: underline;
  }
}

img {
  max-width: 100%;
  height: auto;
  border: 0;
}

h1, h2, h3, h4, h5, h6 {
  margin: 1.5em 0 1em;
  line-height: 1.3;
  font-weight: var(--bolderFontWeight);
}

h1 { font-size: 1.5em; }
h2 { font-size: 1.375em; }
h3 { font-size: 1.25em; }
h4 { font-size: 1.125em; }
h5, h6 { font-size: 1em; }

p { margin: 0 0 1em; }
p:last-child { margin-bottom: 0; }

b, strong { font-weight: var(--boldFontWeight); }

small { font-size: .9em; }

ul, ol {
  margin: 1.5em 0;
  padding: 0 0 0 2em;
  list-style: disc outside;
}

ul ul { list-style-type: circle; }
ol { list-style-type: decimal; }
ol ol { list-style-type: lower-alpha; }
ol ol ol { list-style-type: lower-roman; }

li + li { margin-top: .25em; }
li > ul, li > ol, dd > ul, dd > ol { margin: .5em 0; }
li > p { margin-bottom: .25em; }

dl { margin: 1.5em 0; }
dt { font-weight: var(--boldFontWeight); }
dd {
  margin: .375em;
  padding-left: 1em;

  + dt { margin-top: 1em; }
}

dfn, var { font-style: normal; }

abbr, acronym, dfn {
  cursor: help;
  border-bottom: 1px dotted var(--textColor);
}

pre, code, samp, %pre, %code {
  font-family: var(--monoFont);
  font-weight: normal;
  font-style: normal;
  font-size: .9em;
  color: var(--textColor);
  white-space: pre-wrap;
  direction: ltr;
  -moz-tab-size: 2;
    -o-tab-size: 2;
       tab-size: 2;
}

pre, %pre {
  position: relative;
  margin: 1.5em 0;
  padding: .375rem .625rem;
  line-height: 1.5;
  overflow: auto;
  @extend %box;
}

a > code { color: inherit; }

table {
  margin: 1.5em 0;
  background: none;
  border: 1px solid var(--boxBorder);
  border-collapse: separate;
  border-spacing: 0;
  border-radius: 3px;
  display: inline-block;
  overflow-x: auto;
  max-width: 100%;
}

caption {
  font-weight: var(--boldFontWeight);
  padding: 0 .7em .3em;
}

th, td {
  vertical-align: top;
  padding: .3em .7em;
  padding-bottom: -webkit-calc(.3em + 1px);
  padding-bottom:         calc(.3em + 1px);
  text-align: left;
  white-space: normal !important;
}

th {
  font-weight: var(--boldFontWeight);
  border: 0;
  border-bottom: 1px solid var(--boxBorder);
  border-radius: 0;
  @extend %heading-box;

  &:empty { background: none; }

  + th, + td { border-left: 1px solid var(--boxBorder); }

  tr:first-child > &:first-child { border-top-left-radius: 3px; }
  tr:first-child > &:last-child { border-top-right-radius: 3px; }
  tr:last-child > &:first-child { border-bottom-left-radius: 3px; }
  thead > tr:last-child > &:first-child { border-bottom-left-radius: 0; }
  tr:last-child > & { border-bottom-width: 0; }
  thead > tr:last-child > & { border-bottom-width: 1px; }
}

td {
  background: var(--contentBackground);
  border-bottom: 1px solid var(--boxBorderLight);

  + td { border-left: 1px solid var(--boxBorderLight); }
  tr:last-child > & { border-bottom: 0; }

  > pre:only-child, > p:only-child, > ul:only-child, > ol:only-child {
    margin-top: 0;
    margin-bottom: 0;
  }
  > pre:first-child, > p:first-child, > ul:first-child, > ol:first-child { margin-top: 0; }
  > pre:last-child, > p:last-child, > ul:last-child, > ol:last-child { margin-bottom: 0; }
}

section, main {
  display: block;
  outline: 0;
}

label {
  display: block;
  @extend %user-select-none;
}

input, button {
  display: inline-block;
  margin: 0;
  font-family: inherit;
  font-size: 100%;
  color: var(--textColor);
  line-height: normal;
  @extend %border-box;
}

input[type=checkbox] {
  width: 1rem;
  height: 1rem;
  cursor: pointer;
}

button {
  padding: 0;
  background: none;
  border: 0;
  cursor: pointer;
}

button, input[type="search"] {
  -webkit-appearance: none;
          appearance: none;
}

button:focus {
  outline: 1px dotted;
  outline: -webkit-focus-ring-color auto 5px;
}

img, iframe {
  background: var(--externalsBackground);
}

input[type="search"]::-webkit-search-cancel-button,
input[type="search"]::-webkit-search-decoration {
  -webkit-appearance: none;
}

::-ms-clear { display: none; }

::-moz-focus-inner {
  padding: 0 !important;
  border: 0 !important;
}

::-webkit-input-placeholder { color: var(--textColorLighter); }
::-moz-placeholder          { color: var(--textColorLighter); opacity: 1; }
:-ms-input-placeholder      { color: var(--textColorLighter); }

body:not(._native-scrollbars) {
  *::-webkit-scrollbar { -webkit-appearance: none; }
  *::-webkit-scrollbar:vertical { width: 16px; }
  *::-webkit-scrollbar:horizontal { height: 16px; }

  *::-webkit-scrollbar-button,
  *::-webkit-scrollbar-corner { display: none; }

  *::-webkit-scrollbar-track {
    background: var(--contentBackground);
    border: 1px solid var(--contentBackground);

    &:hover {
      background: var(--sidebarBackground);
      border-color: var(--sidebarBorder);
    }

    &:vertical { border-width: 0 0 0 1px; }

    &:vertical:corner-present {
      border-width: 0 0 1px 1px;
      border-radius: 0 0 0 2px;
    }

    &:horizontal {
      border-width: 1px 1px 0 1px;
      border-radius: 2px 2px 0 0;
    }
  }

  *::-webkit-scrollbar-thumb {
    min-height: 2rem;
    background: var(--scrollbarColor);
    background-clip: padding-box;
    border: 5px solid rgba(black, 0);
    border-radius: 10px;

    &:hover,
    &:active {
      background-color: var(--scrollbarColorHover);
      border-width: 4px;
    }
  }
}