fediversity.eu/presentation/style.css

:root {
  /* XXX: maybe use light-dark() once it's more widely supported */
  color-scheme: light dark;
  --highlight: rgb(255, 110, 0);
  --background: white;
  --text-color: black;
  --shadow: rgba(0,0,0,0.1);
  scrollbar-gutter: stable;
}

@media (prefers-color-scheme: dark) {
  :root {
    --background: black;
    --text-color: #f0f0f0;
    --shadow: rgba(255,255,255,0.2);
  }
}

body {
  font-family: Heebo, sans-serif;
  color: var(--text-color);
  background-color: var(--background);
  padding: 1em;
}

section {
  max-width: 50em;
  margin: auto;
  margin-top: 1em;
}

h1, h2, h3, h4, h5, h6 {
  font-family: Signika, sans-serif;
  margin-top: 0;
}

h1 {
  font-size: 2em;
}

header > nav {
  font-family: Signika, sans-serif;
  margin-bottom: 2em;
}

a:visited,
a
{
  color: var(--highlight);
  text-decoration: none;
}

header a:visited,
header a
{
  color: var(--text-color);
}

header a {
  text-decoration: none;
}

header a:hover,
header li:hover
{
  color: var(--highlight);
}

header nav ul {
  padding: 0;
}

header > nav ul li {
  list-style-type: none;
}

header > nav > ul {
  display: flex;
  justify-content: space-between;
  align-items: center;
  max-width: 60em;
  margin: auto;
}

header > nav > ul > li:first-child a {
  content: url('ngi-fediversity.svg');
  display: inline-block;
  height: 2em;
  margin-right: 5vw;
}

header > nav > ul > li:last-child > a {
  border: 1pt solid var(--text-color);
  padding: 0.5em 1em 0.5em 1em;
  border-radius: 3pt;
  margin-left: 5vw;
}

header > nav > ul > li:last-child:hover > a {
  color: var(--background);
  background-color: var(--highlight);
  border-color: var(--background);
}

header > nav > ul > li > details > nav {
  position: absolute;
  /*top: 2em;*/
  background: var(--background);
  min-width: max-content;
  margin-top: 1em;
  padding: 1em;
  box-shadow: 0 0 1em var(--shadow);
  z-index: 0;
}

header > nav > ul > li > details {
  display: block;
  /*padding: 1em 0;*/
  cursor: pointer;
}

header > nav > ul > li > details[open] > summary {
  color: var(--highlight);
}

header > nav > ul > li > details > nav ul li {
  padding: 0.25em 0;
}

#menu-toggle {
  display: none;
}

@media (max-width: 50em) {
  #menu-toggle:checked ~ nav > ul > li {
    display: block;
  }

  #menu-toggle::before {
    content: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='24' height='24' viewBox='0 0 20 20'%3E%3Cpath d='M0 3h20v2H0V3z m0 6h20v2H0V9z m0 6h20v2H0V0z'/%3E%3C/svg%3E");
    display: block;
  }

  #menu-toggle:checked::before {
    content: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='24' height='24' viewBox='0 0 20 20'%3E%3Cpolygon points='11 9 22 9 22 11 11 11 11 22 9 22 9 11 -2 11 -2 9 9 9 9 -2 11 -2' transform='rotate(45 10 10)'/%3E%3C/svg%3E");
  }

  header > nav {
    margin-bottom: 1em;
  };

  header > nav > ul > li:not(:first-child) {
    display: none;
  }

  header > nav > ul {
    flex-direction: column;
  }

  header > nav > ul > li {
    margin: 0;
    padding: 0;
    text-align: center;
    font-size: 1.3em;
  }

  header > nav > ul > li > details{
    /* compensate for collapse triangle */
    margin-left: -1rem;
  }

  header > nav > ul > li > details > nav {
    position: relative;
    margin: 0;
    padding: 0 0 0.5em 0;
    box-shadow: none;
    /* compensate back for container's collapse triangle compensation */
    margin-left: 1rem;
  }

  header > nav > ul > li > details > nav ul li {
    padding: 0;
    font-size: 1.15rem;
  }

  header > nav > ul::before {
    content: "";
    display: flex;
    justify-content: space-between;
    align-items: center;
  }

  header > nav > ul > li:first-child {
    display: block;
  }

  header > nav > ul > li:first-child a {
    margin: 0 0 0.5em 0;
    height: 2.5em;
  }

  header > nav > ul > li:last-child {
    margin: 1em 0 0 0;
  }

  header > nav > ul > li:last-child a {
    margin: 0;
  }

  header {
    position: relative;
  }

  /* for some reason this must be at the end to work */
  #menu-toggle {
    display: block;
    position: absolute;
    right: 1em;
    top: 0.5em;
    appearance: none;
    cursor: pointer;
  }
}