:root {
  /* Font stacks from https://systemfontstack.com/ */
  --sans-serif-fonts: Seravek, 'Gill Sans Nova', Ubuntu, Calibri, 'DejaVu Sans', source-sans-pro, sans-serif;
  --serif-fonts: Charter, 'Bitstream Charter', 'Sitka Text', Cambria, serif;
  --mono-fonts: Menlo, Consolas, Monaco, Liberation Mono, Lucida Console, monospace;


  font-family: var(--serif-fonts);
  font-weight: normal;
  font-size: 18px;
  line-height: 1.6;

  font-synthesis: none;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  margin: 0;
  font-size: 1rem;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
}

main {
  max-width: 700px;
  margin: 0 auto;
  padding: 1rem;

  background-color: #eeeeee;
  color: #333333;
}

a {
  color: #0066cc;
  text-decoration: underline;
}

a:hover {
  color: #004999;
}

p {
  margin-bottom: 1em;
}

h1, h2, h3, h4, h5, h6 {
  font-family: var(--sans-serif-fonts);
  font-weight: bold;
}

h1 {
  font-size: 2rem;
  margin-top: 2rem;
  margin-bottom: 1rem;
}

h2 {
  font-size: 1.75rem;
  margin-top: 1.5rem;
  margin-bottom: 0.75rem;
}

h3 {
  font-size: 1.5rem;
  margin-top: 1.25rem;
  margin-bottom: 0.75rem;
}

/* TODO: cover h4, h5, h6 */

ul, ol {
  margin: 1em 0 1em 0;
  line-height: 1.6;
}

li {
  margin: 0.5em 0;
}

code, pre {
  font-family: var(--mono-fonts);
}

pre {
  border: 1px dotted #ccc;
}

.nav-wide-wrapper { display: none; }
#theme-toggle { display: none; }

.menu-title {
  font-family: var(--sans-serif-fonts);
  font-weight: normal;
  font-size: 1.5rem;
  font-style: italic;
}

.exercise {
  background-color: #f0e0d0;
  padding: 1rem;
}

.exercise .solution {
  border: 1px dotted #000000;
  padding: 1rem;
  display: none;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

figure {
  margin: 1rem 0;
  text-align: center;
}

figcaption {
  font-size: 0.9rem;
  color: #555;
}

@media (max-width: 768px) {
  body {
    font-size: 16px;
  }

  .content {
    margin-left: 0;
    max-width: 100%;
    padding: 1rem;
  }
}

@media (prefers-color-scheme: light) {
  :root {
    color: #213547;
    background-color: #ffffff;
  }
  a:hover {
    color: #747bff;
  }
  button {
    background-color: #f9f9f9;
  }
}

@media (prefers-color-scheme: dark) {
  :root {
    color: #213547;
    background-color: #ffffff;
  }
  a:hover {
    color: #747bff;
  }
  button {
    background-color: #f9f9f9;
  }
}