:root {
  --bg: #121212;
  --bg-soft: #1a1a1a;
  --ink: #efefef;
  --ink-dim: #b1b1b1;
  --line: #d8d8d8;
  --accent: #ff4d1f;
  --sidebar-width: 300px;
  --font-sans: "Barlow", "Segoe UI", "Trebuchet MS", Arial, sans-serif;
  --font-display: "Barlow Condensed", "Arial Narrow", "Franklin Gothic Medium", sans-serif;
  --font-mono: "IBM Plex Mono", "SFMono-Regular", Consolas, "Liberation Mono", monospace;
}

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

html,
body {
  margin: 0;
  padding: 0;
}

body {
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-sans);
  line-height: 1.62;
  font-size: 18px;
  min-height: 100vh;
  display: flex;
}

.skip-link {
  position: absolute;
  left: 1rem;
  top: -100%;
  z-index: 10;
  background: var(--accent);
  color: #060606;
  text-decoration: none;
  padding: 0.6rem 0.8rem;
  font-weight: 700;
}

.skip-link:focus {
  top: 1rem;
}

.sidebar {
  width: var(--sidebar-width);
  border-right: 3px solid var(--line);
  padding: 2rem 1.5rem 2.2rem;
  position: fixed;
  inset: 0 auto 0 0;
  overflow-y: auto;
  background: var(--bg-soft);
}

.site-title {
  margin: 0;
  padding-bottom: 1.1rem;
  border-bottom: 3px solid var(--line);
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.35rem;
  letter-spacing: 0.02em;
  text-transform: uppercase;
  line-height: 1.1;
}

.menu-toggle {
  display: none;
}

.sidebar nav ul {
  list-style: none;
  padding: 0;
  margin: 1.4rem 0 0;
}

.sidebar nav li {
  margin: 0.2rem 0;
}

.sidebar nav a {
  display: block;
  color: var(--ink);
  text-decoration: none;
  text-transform: uppercase;
  letter-spacing: 0.03em;
  font-weight: 800;
  font-size: 0.82rem;
  line-height: 1.2;
  padding: 0.52rem 0.55rem;
  border: 2px solid transparent;
}

.sidebar nav a:hover,
.sidebar nav a:focus-visible {
  border-color: var(--accent);
  color: var(--bg);
  background: var(--accent);
  outline: none;
}

.sidebar nav a.nav-current {
  border-color: var(--accent);
  color: var(--bg);
  background: var(--accent);
}

.chapters {
  margin-top: 1.6rem;
  border-top: 3px solid var(--line);
  padding-top: 1.1rem;
}

.chapters h2 {
  font-family: var(--font-display);
  font-size: 0.9rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--ink-dim);
  margin: 0 0 0.5rem;
}

main {
  margin-left: var(--sidebar-width);
  width: min(88ch, calc(100vw - var(--sidebar-width) - 2.5rem));
  padding: 3.25rem clamp(1.25rem, 2vw + 0.65rem, 2.6rem) 4.5rem;
}

h1,
h2,
h3,
h4,
h5,
h6 {
  font-family: var(--font-display);
  font-weight: 700;
  letter-spacing: 0.01em;
  text-transform: uppercase;
  line-height: 1.22;
}

h1 {
  margin-top: 0;
  font-size: clamp(1.85rem, 3.5vw, 2.7rem);
  padding-bottom: 0.65rem;
  border-bottom: 4px solid var(--line);
}

h2 {
  margin-top: 2.8rem;
  font-size: clamp(1.3rem, 1.08rem + 1vw, 1.9rem);
}

h3 {
  margin-top: 2rem;
  font-size: clamp(1.08rem, 1rem + 0.45vw, 1.25rem);
}

p {
  margin: 1rem 0 1.35rem;
}

ul,
ol {
  margin: 1rem 0 1.4rem;
  padding-left: 1.35rem;
}

li {
  margin-bottom: 0.42rem;
}

a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 2px solid var(--accent);
}

a:hover,
a:focus-visible {
  color: var(--bg);
  background: var(--accent);
  border-color: var(--accent);
  outline: none;
}

blockquote {
  margin: 1.6rem 0;
  padding: 0.5rem 0.7rem;
  border: 2px solid var(--accent);
  color: var(--ink);
  background: #111111;
}

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

code {
  background: #161616;
  border: 1px solid #2b2b2b;
  padding: 0.15rem 0.35rem;
}

pre {
  background: #0a0a0a;
  border: 2px solid var(--line);
  padding: 1rem;
  overflow-x: auto;
}

pre code {
  background: transparent;
  padding: 0;
}

@media (max-width: 980px) {
  :root {
    --sidebar-width: 270px;
  }
}

@media (max-width: 820px) {
  body {
    display: block;
  }

  .sidebar {
    position: relative;
    width: 100%;
    inset: 0 0 auto 0;
    border-right: none;
    border-bottom: 3px solid var(--line);
    z-index: 2;
    padding: 0.85rem 0.85rem 0.9rem;
    max-height: none;
  }

  .site-title {
    font-size: 1rem;
    padding-bottom: 0.45rem;
    border-bottom: 0;
  }

  .menu-toggle {
    display: inline-block;
    font-family: var(--font-display);
    text-transform: uppercase;
    letter-spacing: 0.06em;
    font-size: 0.8rem;
    border: 2px solid var(--line);
    background: transparent;
    color: var(--ink);
    padding: 0.32rem 0.6rem;
    cursor: pointer;
  }

  .menu-toggle:hover,
  .menu-toggle:focus-visible {
    background: var(--accent);
    color: var(--bg);
    border-color: var(--accent);
    outline: none;
  }

  .sidebar-menu {
    display: none;
  }

  .sidebar.menu-open .sidebar-menu {
    display: block;
  }

  .sidebar nav ul {
    margin-top: 0.6rem;
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 0.3rem;
  }

  .sidebar nav a {
    font-size: 0.7rem;
    padding: 0.38rem 0.4rem;
  }

  .chapters {
    margin-top: 0.6rem;
    padding-top: 0.6rem;
  }

  main {
    margin-left: 0;
    width: 100%;
    padding: 1.4rem 1rem 2.5rem;
  }
}