$font-size: 17px;
$heading-font-size: 18px;
$line-height: 1.4;

$page-item-indent-max-chars: 3ch;
$page-item-indent-pad: 2ch;
$page-item-indent: $page-item-indent-max-chars + $page-item-indent-pad;

$page-subitem-indent: 4ch;

:root {
  --gray1: hsl(270, 0%, 9.7%); // bg
  --gray2: hsl(270, 1%, 29%); // bg-plus
  --gray3: hsl(270, 2%, 54%); // text-minus
  --gray4: hsl(270, 2%, 73%); // text
  --gray5: hsl(270, 2%, 100%); // text-plus

  --select-bg: hsla(270, 2%, 100%, 0.996);
  --select-fg: var(--gray1);

  --page-item-prefix: var(--gray3);

  --link-idle: var(--gray5);
  --link-hover-bg: var(--gray5);
  --link-hover-fg: var(--gray1);

  --heading: var(--gray5);
}

@function px-to-em($s, $b: $font-size) {
  @return 1 / ($b / 1px) * ($s / 1px) * 1em;
}

@function str-repeat($s, $n) {
  $r: "";
  @while $n > 0 {
    $r: $r + $s;
    $n: $n - 1;
  }
  @return $r;
}

@mixin item($prefix: "") {
  position: relative;

  &::before {
    position: absolute;
    content: $prefix;
    box-sizing: border-box;
    display: inline-block;
    font-size: 1rem;
    margin-left: -1 * $page-item-indent;
    padding-right: $page-item-indent-pad;
    width: $page-item-indent;
    color: var(--page-item-prefix);
    font-weight: normal;
    text-align: right;
  }

  @media (max-width: 700px) {
    &::before {
      display: none;
    }
  }
}

@keyframes flicker {
  0% {
    opacity: 0;
  }
  25% {
    opacity: 1;
  }
  50% {
    opacity: 0;
  }
}

::selection {
  color: var(--select-fg);
  background-color: var(--select-bg);
}

html {
  font-family: "Iosevka Term SS09";
  font-feature-settings: "calt" 0, "PURS" 1;
  font-size: px-to-em($font-size, 16px);
  line-height: $line-height;
  background-color: var(--gray1);
  color: var(--gray4);
}

body {
  margin: 2em 2em 2em 1em;
  padding: 0;

  @media (max-width: 700px) {
    margin: 1em;
  }
}

main {
  max-width: 80ch;
  margin: 0 auto;
  padding-left: $page-item-indent;

  @media (max-width: 700px) {
    padding-left: 0;
  }
}

header {
  margin-left: -1 * $page-item-indent;
  margin-bottom: $line-height * 2rem;
  padding-left: $page-item-indent;
  overflow: hidden;

  &::after {
    position: relative;
    z-index: -10;
    content: str-repeat("░", 120);
    display: block;
    height: $line-height;
    margin-top: px-to-em(2px);
    margin-left: -1 * $page-item-indent;
    padding-top: px-to-em(2px);
    color: var(--gray3);
    border-top: 1px solid var(--gray3);
  }

  @media (max-width: 700px) {
    padding-left: 0;

    &,
    &::after {
      margin-left: 0;
    }
  }
}

pre,
code {
  font-family: "Iosevka Term SS09";
  //font-feature-settings: "calt" 0, "PURS" 0;
}

pre {
  @include item;

  margin: 0;
  color: var(--gray3);

  &::before {
    content: str-repeat("``\A", 40);
    height: 100%;
    color: var(--page-item-prefix);
    overflow: hidden;
  }

  strong {
    font-weight: normal;
  }
}

strong {
  color: var(--gray5);
  font-weight: bold;
}

ul,
ol {
  margin: ($line-height * 1rem) 0 0;
  padding: 0;
  list-style: none;

  > li {
    &::before {
      display: inline-block;
      color: var(--page-item-prefix);
      text-align: right;
    }
  }
}

ul {
  > li::before {
    content: "-";
    padding-right: $page-subitem-indent - 1;
  }

  &.refs {
    > li {
      @include item("|>");
    }
  }
}

ol {
  counter-reset: cnt;

  > li {
    counter-increment: cnt;

    &::before {
      content: counter(cnt) ".";
      padding-right: $page-subitem-indent - 2;
    }
  }
}

h1,
h2,
h3 {
  @include item;

  margin: ($line-height * 2rem) 0 0;

  + h1,
  + h2,
  + h3 {
    margin-top: $line-height * 1rem;
  }
}

h1 {
  text-transform: uppercase;
  font-size: px-to-em($heading-font-size);
  color: var(--heading);

  &::before {
    content: "#";
  }
}

h2 {
  font-size: 1em;
  color: var(--heading);

  &::before {
    content: "##";
  }
}

h3 {
  font-size: 1em;

  &::before {
    content: "###";
  }
}

p {
  margin: ($line-height * 1em) 0 0;
}

a {
  position: relative;
  z-index: 1000;
  padding: 0.1em 0.3em;
  margin: 0 -0.3em;
  color: var(--link-idle);

  &:hover {
    background-color: var(--link-hover-bg);
    color: var(--link-hover-fg);
    text-decoration: none;
    animation-duration: 0.07s;
    animation-name: flicker;
    animation-timing-function: step-start;
    animation-iteration-count: 3;
  }
}

hr {
  height: 1px;
  margin: ($line-height * 2rem) 0;
  margin-left: -1 * $page-item-indent;
  background-color: var(--gray2);
  border: 0;

  @media (max-width: 700px) {
    margin-left: 0;
  }
}

blockquote {
  position: relative;
  margin: ($line-height * 1rem) 0 0;
  padding-left: calc(#{$page-subitem-indent} - 2px);
  border-left: 2px solid var(--gray2);

  /*&::before {
    content: str-repeat(">\A", 50);
    position: absolute;
    height: 100%;
    margin-left: -1 * $page-subitem-indent;
    color: var(--page-item-prefix);
    overflow: hidden;
    white-space: pre;
  }*/
}