@layer reset {
  *,
  *::before,
  *::after {
    box-sizing: border-box;
  }

  body {
    margin: 0;
  }
}

@layer base {
  main {
    height: 100vh;
    overflow: scroll;
    scroll-snap-type: y mandatory;
  }

  main > section {
    height: 100%;
    scroll-snap-align: center;
    scroll-snap-stop: always;
  }
}

@layer theme {
  :root {
    --c-fg: black;
    --c-bg: snow;
    --c-primary: royalblue;
    --c-neutral: lavender;
    --c-notice: orange;
    --c-lines: var(--c-primary);
    --c-shadows: var(--c-neutral);
    --slide-width: 65ch;
    --slide-motion: 100ms ease;

    font-family: sans-serif;
    background-color: var(--c-bg);
    color: var(--c-fg);
  }

  ::selection {
    background-color: var(--c-primary);
    color: var(--c-bg);
  }

  main {
    font-size: clamp(1rem, 4vw, 1.25rem);
    padding: 1rem;
  }

  header {
    position: fixed;
    width: 100vw;
    z-index: 10;
  }

  footer {
    position: fixed;
    bottom: 0;
    width: 100vw;
  }

  :is(header, footer) > ul {
    margin: 0;
    padding: 1rem;
    list-style: none;
    display: flex;
    justify-content: space-between;
    align-items: center;
  }

  :is(header, footer) > ul > li {
    margin: 0;
  }

  section {
    width: min(var(--slide-width), 100%);
    margin-inline: auto;
    padding-block: 2rem;
    overflow: hidden;
  }

  section > :is(h1, h2, h3),
  hgroup {
    margin-block-end: 1.5rem;
  }

  section > h1,
  hgroup:has(> h1) {
    margin-block-start: 8rem;
  }

  hgroup:has(> h1) > p {
    font-size: 2em;
  }

  section > h3,
  hgroup:has(> h3) {
    border-bottom: 2px solid var(--c-lines);
  }

  section > h3 {
    padding-block-end: 1.5rem;
  }

  h1 {
    font-size: 3em;
  }

  h2 {
    font-size: 2em;
  }

  h3 {
    font-size: 1.5em;
  }

  a {
    color: var(--c-primary);
    text-decoration: none;
  }

  :is(h1, h2, h3) > a[href^="#"]:not(:empty)::before {
    content: "# ";
    transition: opacity var(--slide-motion);
    opacity: 0.6;
  }

  :is(h1, h2, h3) > a[href^="#"]:not(:empty):hover::before {
    opacity: 0.9;
  }

  blockquote {
    opacity: 0.8;
    margin-inline-start: 0;
    border-inline-start: 4px solid var(--c-lines);
    padding-inline-start: 0.5rem;
  }

  pre {
    position: relative;
    padding: 1rem;
    margin-inline: 4px;
    border-radius: 4px;
    border: 2px solid var(--c-lines);
    box-shadow: -4px 4px 0 0 var(--c-shadows);
    background-color: var(--c-neutral);
    overflow: scroll;
  }

  :not(pre) > code {
    padding-inline: 4px;
    border-radius: 4px;
    background-color: var(--c-shadows);
  }

  :is(ol, ul) > li {
    margin-block-end: 0.5rem;
  }

  details {
    padding: 0.5rem 1rem;
    border-radius: 4px;
    border: 2px dashed var(--c-lines);
  }

  details > summary {
    padding: 16px 0;
    color: var(--c-primary);
  }

  details > summary::marker {
    content: "⟟ ";
  }

  details[open] > summary {
    border-bottom: 2px dashed var(--c-lines);
  }

  abbr {
    border-radius: 4px;
    padding: 4px;
    background-color: var(--c-notice);
  }

  button {
    all: unset;
    cursor: pointer;
    color: var(--c-primary);
    background-color: var(--c-bg);
    border: 2px solid var(--c-primary);
    border-radius: 4px;
    padding: 4px;
    transition: all var(--slide-motion);
  }

  button:hover {
    color: var(--c-bg);
    background-color: var(--c-primary);
    box-shadow: -2px 2px 0 0 var(--c-shadows);
    transform: translateY(-2px) translateX(2px);
  }

  figure {
    font-size: 1rem;
    text-align: center;
    margin-inline: 4px;
  }

  figure > img {
    width: 100%;
    border: 2px solid var(--c-lines);
    border-radius: 4px;
    box-shadow: -4px 4px 0 0 var(--c-shadows);
  }

  figcaption {
    margin-top: 0.75rem;
    text-align: start;
  }

  figcaption::before {
    content: "⤷ ";
  }
}