emacs-config/misc/org-css/_theme.scss

$blue: #3a81c3;
$green: #2d9574;
$red: #ba2f59;
$orange: #dc752f;
$cyan: #2aa1ae;
$purple: #715ab1;

$accent: var(--accent);
$accent-dark: var(--accent-dark);

$code-foreground: var(--code-foreground);
$code-background: var(--code-background);
$code-func: var(--code-func);
$code-constant: var(--code-const);
$code-regex: var(--code-regex);

$back-white: var(--back-white);
$back-light: var(--back-light);
$back-medium: var(--back-medium);

$text-light: var(--text-light);
$text-gray: var(--text-gray);
$text-medium: var(--text-medium);
$text-dark: var(--text-dark);

@media (prefers-color-scheme: light) {
  #page {
    --accent: #002642;
    --accent-dark: #00151c;

    --code-foreground: #2c3e50;
    --code-background: #f5f5f5;
    --code-func: #6c3163;
    --code-const: #4e3163;
    --code-regex: #655370;

    --back-white: #fff;
    --back-light: #f0eeed;
    --back-medium: #c8c8c8;

    --text-light: #7b7b7b;
    --text-gray: #444;
    --text-medium: #222;
    --text-dark: #000;

    --switch-icon: "🌚";
    --switch-shadow-color: #373d4e;
    --switch-text: "dark mode?";
  }

  #theme-switch:checked ~ #page {
      --accent: #002642;
      --accent-dark: #daf1ff;

      --code-foreground: #a1a8ae;
      --code-background: #222;
      --code-func: #bd56ad;
      --code-const: #8755ab;
      --code-regex: #a184b3;

      --back-white: #000;
      --back-light: #181818;
      --back-medium: #444;

      --text-light: #7b7b7b;
      --text-gray: #c8c8c8;
      --text-medium: #ddd;
      --text-dark: #efefef;

      --switch-icon: "🌝";
      --switch-shadow-color: #fce477;
      --switch-text: "light mode?";
      img.invertible, object[type="image/svg+xml"].invertible, img.org-latex {
          filter: invert(90.5%) hue-rotate(180deg) sepia(1%);
      }
  }
}

@media (prefers-color-scheme: dark) {
  #theme-switch:checked ~ #page {
    --accent: #002642;
    --accent-dark: #00151c;

    --code-foreground: #2c3e50;
    --code-background: #f5f5f5;
    --code-func: #6c3163;
    --code-const: #4e3163;
    --code-regex: #655370;

    --back-white: #fff;
    --back-light: #f0eeed;
    --back-medium: #c8c8c8;

    --text-light: #7b7b7b;
    --text-gray: #444;
    --text-medium: #222;
    --text-dark: #000;

    --switch-icon: "🌚";
    --switch-shadow-color: #373d4e;
    --switch-text: "dark mode?";
    img.invertible, object[type="image/svg+xml"].invertible, img.org-latex {
      filter: invert(7%) sepia(4%);
    }
  }

  #page {
      --accent: #002642;
      --accent-dark: #daf1ff;

      --code-foreground: #a1a8ae;
      --code-background: #222;
      --code-func: #bd56ad;
      --code-const: #8755ab;
      --code-regex: #a184b3;

      --back-white: #000;
      --back-light: #181818;
      --back-medium: #444;

      --text-light: #7b7b7b;
      --text-gray: #c8c8c8;
      --text-medium: #ddd;
      --text-dark: #efefef;

      --switch-icon: "🌝";
      --switch-shadow-color: #fce477;
      --switch-text: "light mode?";
      img.invertible, object[type="image/svg+xml"].invertible, img.org-latex {
          filter: invert(90.5%) hue-rotate(180deg) sepia(1%);
      }
  }
}

#theme-switch {
    display: none;
}

#switch-label {
    position: fixed;
    bottom: 4rem;
    left: 3rem;
}

#switch-label::before {
  content: var(--switch-icon);
  font-size: 20px;
  transition: text-shadow .2s;
}

#switch-label::after {
  content: var(--switch-text);
  color: var(--switch-shadow-color);
  font-size: 12px;
  visibility: hidden;
  margin-left: 0.5em;
  z-index: 1;
  position: fixed;
  bottom: calc(4rem - 25px);
  left: calc(3rem - 10px);
}

@media (max-width: 1000px) {
    #switch-label {
        left: auto;
        bottom: auto;
        right: 1vw;
        top: 1vh;
        &::after {
          position: fixed;
          top: calc(1vh + 3px);
          right: calc(1vw + 30px);
          left: auto;
          bottom: auto;
        }
    }
}

#theme-switch:focus ~ #page #switch-label,
#switch-label:hover {
  &::before {
  text-shadow: 0 0 15px var(--switch-shadow-color);
  }
  &::after {
    visibility: visible;
  }
}