/* RustyVulkan guide: palette and type taken from vulkan.org
   (crimson #ac1933, charcoal #1b1b1b, Poppins headings, Lato body). */

:root {
  --bg: #ffffff;
  --surface: #f6f6f6;
  --surface-2: #ececec;
  --fg: #1b1b1b;
  --muted: #5c5c5c;
  --line: #d6d6d6;
  --accent: #ac1933;
  --accent-2: #d2475f;
  --accent-soft: #f7e3e7;
  --chrome: #1b1b1b;
  --chrome-fg: #f2f2f2;
  --gl: #2f6aa8;
  --gl-soft: #e6eef8;
  --rust: #c4421f;
  --rust-soft: #fbe9e2;
  --aside: #8a6d1a;
  --aside-soft: #f8f1dc;
  --code-bg: #f6f6f6;
  --shadow: 0 10px 30px rgba(0, 0, 0, 0.18);
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #141414;
    --surface: #1f1f1f;
    --surface-2: #2a2a2a;
    --fg: #e8e8e8;
    --muted: #a3a3a3;
    --line: #383838;
    --accent: #e0546b;
    --accent-2: #f07f91;
    --accent-soft: #3a1820;
    --chrome: #0b0b0b;
    --chrome-fg: #f2f2f2;
    --gl: #7fb0e6;
    --gl-soft: #18263a;
    --rust: #f08a63;
    --rust-soft: #3a2018;
    --aside: #e2c46c;
    --aside-soft: #332a12;
    --code-bg: #1c1c1c;
    --shadow: 0 10px 30px rgba(0, 0, 0, 0.6);
    color-scheme: dark;
  }
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }
[id] { scroll-margin-top: 4.5rem; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: "Lato", system-ui, -apple-system, "Segoe UI", sans-serif;
  font-size: 18px;
  line-height: 1.65;
}

h1, h2, h3, h4, .brand, .kicker, .tag, .dive-divider span, .callout-title, .pager a {
  font-family: "Poppins", system-ui, sans-serif;
}

h1 { font-size: clamp(1.9rem, 4vw, 2.6rem); line-height: 1.2; margin: 0.2em 0 0.3em; font-weight: 700; }
h2 { font-size: 1.5rem; line-height: 1.3; margin: 2.2em 0 0.6em; font-weight: 600; }
h3 { font-size: 1.15rem; margin: 1.8em 0 0.4em; font-weight: 600; }

a { color: var(--accent); text-underline-offset: 2px; }
a:hover { color: var(--accent-2); }

code, pre { font-family: "JetBrains Mono", ui-monospace, Menlo, monospace; font-variant-ligatures: none; }
:not(pre) > code {
  font-size: 0.86em;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 0.05em 0.3em;
  overflow-wrap: anywhere;
}

dfn { font-style: normal; font-weight: 700; color: var(--accent); }

/* ---- Site chrome -------------------------------------------------------- */

header.site, footer.site {
  background: var(--chrome);
  color: var(--chrome-fg);
}

header.site {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.8rem 16px;
  border-bottom: 4px solid #ac1933;
  position: sticky;
  top: 0;
  z-index: 10;
}

header.site a { color: var(--chrome-fg); text-decoration: none; }
.brand { font-weight: 700; font-size: 1.05rem; letter-spacing: 0.02em; }
.brand span { color: #e0546b; font-weight: 400; }
.toc-link {
  font-family: "Poppins", sans-serif;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.25em;
}
.toc-link:hover { color: #e0546b !important; }

footer.site {
  margin-top: 4rem;
  padding: 1.5rem 16px;
  text-align: center;
  font-size: 0.85rem;
  color: #b8b8b8;
}
footer.site a { color: #f07f91; }
footer.site code { background: #2a2a2a; border-color: #3a3a3a; color: #e8e8e8; }

/* ---- Chapter layout ----------------------------------------------------- */

main.chapter {
  max-width: 76ch;
  margin: 0 auto;
  padding: 0 16px;
}

.chapter-head { padding: 2.5rem 0 0.5rem; border-bottom: 1px solid var(--line); margin-bottom: 1rem; }
.kicker {
  margin: 0;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.2em;
  color: var(--accent);
  font-weight: 600;
}
.readtime { color: var(--muted); }
.lede { font-size: 1.2rem; color: var(--muted); margin: 0 0 1.5rem; }

.tag {
  display: inline-block;
  vertical-align: middle;
  font-size: 0.65rem;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  background: var(--accent);
  color: #fff;
  padding: 0.25em 0.7em;
  border-radius: 999px;
  margin-right: 0.5em;
  position: relative;
  top: -0.15em;
}

.dive-divider {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin: 3.5rem 0 1rem;
}
.dive-divider::before, .dive-divider::after {
  content: "";
  flex: 1;
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--accent), transparent);
}
.dive-divider span {
  background: var(--accent);
  color: #fff;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.2em;
  padding: 0.45em 1.2em;
  border-radius: 999px;
  white-space: nowrap;
}
.dive-intro { color: var(--muted); font-style: italic; text-align: center; margin-top: 0; }

/* ---- Figures ------------------------------------------------------------ */

figure { margin: 1.6rem 0; }

figure.code {
  border: 1px solid var(--line);
  border-radius: 8px;
  overflow: hidden;
  background: var(--code-bg);
}
figure.code pre {
  margin: 0;
  padding: 1rem 1.1rem;
  overflow-x: auto;
  font-size: 0.8rem;
  line-height: 1.55;
  tab-size: 4;
}
figure.code pre code.hljs { background: transparent; padding: 0; }
figure.code figcaption {
  font-family: "JetBrains Mono", ui-monospace, monospace;
  font-size: 0.72rem;
  color: var(--muted);
  background: var(--surface-2);
  border-top: 1px solid var(--line);
  padding: 0.35rem 1.1rem;
  overflow-wrap: anywhere;
}

figure.diagram {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 1rem;
}
figure.diagram svg { display: block; width: 100%; height: auto; max-width: 100%; }
figure.diagram figcaption, figure.shot figcaption {
  font-size: 0.85rem;
  color: var(--muted);
  margin-top: 0.6rem;
  text-align: center;
}
figure.shot img { width: 100%; height: auto; border-radius: 8px; box-shadow: var(--shadow); display: block; }

/* SVG helpers: diagrams use these classes so both themes stay legible. */
svg text { font-family: "Lato", system-ui, sans-serif; fill: var(--fg); }
svg .mono { font-family: "JetBrains Mono", ui-monospace, monospace; }
svg .muted { fill: var(--muted); }
svg .box { fill: var(--bg); stroke: var(--line); stroke-width: 1.5; }
svg .box-accent { fill: var(--accent-soft); stroke: var(--accent); stroke-width: 1.5; }
svg .box-gl { fill: var(--gl-soft); stroke: var(--gl); stroke-width: 1.5; }
svg .box-rust { fill: var(--rust-soft); stroke: var(--rust); stroke-width: 1.5; }
svg .box-aside { fill: var(--aside-soft); stroke: var(--aside); stroke-width: 1.5; }
svg .wire { stroke: var(--muted); stroke-width: 1.6; fill: none; }
svg .wire-accent { stroke: var(--accent); stroke-width: 2; fill: none; }
svg .fill-accent { fill: var(--accent); }
svg .fill-muted { fill: var(--muted); }
svg .fill-gl { fill: var(--gl); }
svg .fill-rust { fill: var(--rust); }
svg .on-accent { fill: var(--bg); }

/* ---- Callouts ----------------------------------------------------------- */

.callout {
  border-left: 4px solid var(--line);
  background: var(--surface);
  border-radius: 0 8px 8px 0;
  padding: 0.8rem 1.1rem;
  margin: 1.6rem 0;
  font-size: 0.95rem;
}
.callout p { margin: 0.4em 0; }
.callout-title {
  font-size: 0.72rem !important;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  font-weight: 700;
  margin: 0 0 0.3em !important;
}
.callout.gl { border-color: var(--gl); background: var(--gl-soft); }
.callout.gl .callout-title { color: var(--gl); }
.callout.gl .callout-title::before { content: "◆ "; }
.callout.rust { border-color: var(--rust); background: var(--rust-soft); }
.callout.rust .callout-title { color: var(--rust); }
.callout.rust .callout-title::before { content: "⚙ "; }
.callout.aside { border-color: var(--aside); background: var(--aside-soft); }
.callout.aside .callout-title { color: var(--aside); }
.callout.aside .callout-title::before { content: "! "; }
.callout figure.code { margin: 0.8rem 0; background: var(--bg); }

/* ---- Recap and pager ---------------------------------------------------- */

.recap {
  background: var(--surface);
  border: 1px solid var(--line);
  border-top: 4px solid var(--accent);
  border-radius: 8px;
  padding: 0.2rem 1.4rem 0.8rem;
  margin-top: 3rem;
}
.recap h2 { margin-top: 1rem; font-size: 1.2rem; }

.pager {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 2.5rem;
  flex-wrap: wrap;
}
.pager a {
  flex: 1 1 14rem;
  display: block;
  text-decoration: none;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 0.8rem 1rem;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--fg);
}
.pager a:hover { border-color: var(--accent); color: var(--accent); }
.pager .next { text-align: right; }

table { border-collapse: collapse; width: 100%; font-size: 0.9rem; margin: 1.2rem 0; display: block; overflow-x: auto; }
th, td { border-bottom: 1px solid var(--line); padding: 0.45rem 0.6rem; text-align: left; vertical-align: top; }
td code { white-space: nowrap; overflow-wrap: normal; }
th { font-family: "Poppins", sans-serif; font-weight: 600; font-size: 0.8rem; }

/* ---- Cover page --------------------------------------------------------- */

.hero {
  background: var(--chrome);
  color: var(--chrome-fg);
  padding: 3rem 16px 0;
  overflow: hidden;
}
.hero-inner { max-width: 1100px; margin: 0 auto; }
.hero .kicker { color: #e0546b; }
.hero h1 { color: #ffffff; font-size: clamp(2.2rem, 6vw, 3.6rem); margin-bottom: 0.2em; }
.hero h1 span { color: #e0546b; }
.hero .pitch { max-width: 62ch; font-size: 1.15rem; color: #cfcfcf; }
.hero .shot { margin: 2.5rem 0 -1px; }
.hero .shot img { border-radius: 10px 10px 0 0; box-shadow: 0 -10px 40px rgba(172, 25, 51, 0.35); }

.cover { max-width: 1100px; margin: 0 auto; padding: 0 16px; }
.cover .intro { max-width: 76ch; }
.legend { display: grid; grid-template-columns: repeat(auto-fit, minmax(16rem, 1fr)); gap: 1rem; }
.legend .callout { margin: 0; }

.part { margin-top: 2.5rem; }
.part h2 {
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.25em;
  color: var(--accent);
  border-bottom: 1px solid var(--line);
  padding-bottom: 0.5rem;
  margin: 0 0 1rem;
}
.cards {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(min(100%, 19rem), 1fr));
  gap: 1rem;
  list-style: none;
  padding: 0;
  margin: 0;
}
.cards a {
  display: flex;
  flex-direction: column;
  height: 100%;
  text-decoration: none;
  color: var(--fg);
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 1rem 1.1rem;
  transition: border-color 0.2s, transform 0.2s;
}
.cards a:hover { border-color: var(--accent); transform: translateY(-2px); }
.cards .num { font-family: "Poppins", sans-serif; font-weight: 700; color: var(--accent); font-size: 0.85rem; }
.cards .title { font-family: "Poppins", sans-serif; font-weight: 600; font-size: 1.05rem; margin: 0.15rem 0 0.35rem; }
.cards .desc { font-size: 0.9rem; color: var(--muted); flex: 1; line-height: 1.5; }
.cards .time { font-size: 0.75rem; color: var(--muted); margin-top: 0.6rem; font-family: "Poppins", sans-serif; }

@media (max-width: 600px) {
  body { font-size: 17px; }
  .hero { padding-top: 2rem; }
}

/* Reading paths and optional experiments share the existing chapter rhythm. */
.chapter-jumps {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1.2rem;
  font-size: 0.85rem;
  margin: 1rem 0 2rem;
}
.overview-next { font-size: 0.9rem; margin-top: 2rem; }
.callout.try { border-color: var(--gl); background: var(--gl-soft); }
.callout.try .callout-title { color: var(--gl); }
kbd {
  font-family: "JetBrains Mono", ui-monospace, monospace;
  font-size: 0.85em;
  padding: 0.05em 0.3em;
  border: 1px solid var(--line);
  border-bottom-width: 2px;
  border-radius: 4px;
  background: var(--surface);
}
.source-page { margin: 2rem auto; max-width: 1100px; padding: 0 16px; }
.source-page h1 { overflow-wrap: anywhere; font-size: 1.5rem; }
.source-page pre { overflow-x: auto; font-size: 0.8rem; line-height: 1.55; }
.source-line:target { background: var(--accent-soft); outline: 1px solid var(--accent); }
.line-number { display: inline-block; min-width: 3.5em; text-align: right; color: var(--muted); text-decoration: none; }