:root {
  --bg: #0d1117;
  --bg-2: #11161e;
  --bg-3: #161c25;
  --line: #232a35;
  --text: #e6edf3;
  --muted: #8b96a8;
  --accent: #58a6ff;
  --accent-2: #3fb950;
  --warn: #d29922;
  --crit: #f85149;
  --highlight: #ffcc66;
}

* { box-sizing: border-box; }

html, body {
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, "Helvetica Neue", Arial, sans-serif;
  line-height: 1.65;
  margin: 0;
  padding: 0;
  font-size: 16px;
}

a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color 0.15s;
}
a:hover { border-color: var(--accent); }

code {
  background: var(--bg-3);
  border: 1px solid var(--line);
  padding: 1px 6px;
  border-radius: 4px;
  font-family: "SF Mono", "JetBrains Mono", Menlo, Consolas, monospace;
  font-size: 0.9em;
}

/* ===== Top nav ===== */
.topnav {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(13, 17, 23, 0.85);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}
.nav-inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 14px 32px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}
.brand {
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--highlight);
  font-size: 14px;
}
.brand-sub {
  color: var(--muted);
  font-weight: 400;
  letter-spacing: 0.04em;
  font-size: 11px;
  text-transform: uppercase;
  margin-left: 6px;
}
.nav-links {
  display: flex;
  gap: 20px;
  flex-wrap: wrap;
}
.nav-links a {
  color: var(--muted);
  font-size: 13px;
  border-bottom: none;
}
.nav-links a:hover { color: var(--text); border-bottom: 1px solid var(--accent); }

/* ===== Hero ===== */
.hero {
  position: relative;
  overflow: hidden;
  padding: 110px 32px 100px;
  border-bottom: 1px solid var(--line);
  background: linear-gradient(180deg, #0d1117 0%, #131a23 100%);
}
.hero-bg {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0.18;
  filter: saturate(1.2) blur(1px);
  z-index: 0;
  pointer-events: none;
}
.hero-inner {
  position: relative;
  z-index: 1;
  max-width: 1100px;
  margin: 0 auto;
}
.kicker {
  color: var(--accent-2);
  letter-spacing: 0.18em;
  font-size: 12px;
  text-transform: uppercase;
  margin: 0 0 18px;
  font-weight: 600;
}
.hero h1 {
  font-size: clamp(2rem, 5vw, 3.6rem);
  line-height: 1.15;
  margin: 0 0 24px;
  letter-spacing: -0.02em;
  font-weight: 700;
}
.lede {
  font-size: 1.15rem;
  color: #c8d1da;
  max-width: 800px;
  margin: 0 0 40px;
}
.hero-stats {
  display: grid;
  grid-template-columns: repeat(4, minmax(140px, 1fr));
  gap: 18px;
  max-width: 880px;
}
.hero-stats > div {
  border: 1px solid var(--line);
  background: rgba(22, 28, 37, 0.55);
  padding: 18px 20px;
  border-radius: 8px;
  display: flex;
  flex-direction: column;
  gap: 4px;
}
.stat-num {
  font-size: 1.9rem;
  font-weight: 700;
  color: var(--highlight);
  letter-spacing: -0.01em;
}
.stat-lbl {
  font-size: 12px;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

/* ===== Sections ===== */
.section {
  padding: 90px 32px;
  max-width: 1100px;
  margin: 0 auto;
}
.section.alt {
  max-width: none;
  background: var(--bg-2);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}
.section.alt > * {
  max-width: 1100px;
  margin-left: auto;
  margin-right: auto;
}
.section h2 {
  font-size: 2rem;
  margin: 0 0 16px;
  letter-spacing: -0.01em;
  border-left: 3px solid var(--accent);
  padding-left: 14px;
}
.section h3 {
  font-size: 1.3rem;
  margin: 28px 0 12px;
  color: var(--text);
}
.section-lede {
  color: #c8d1da;
  max-width: 820px;
  font-size: 1.05rem;
  margin: 0 0 36px;
}

/* ===== Big quote ===== */
.big-quote {
  font-size: 1.35rem;
  line-height: 1.5;
  font-style: italic;
  border: none;
  color: var(--highlight);
  margin: 30px 0 30px;
  padding: 22px 28px;
  background: rgba(255, 204, 102, 0.05);
  border-left: 3px solid var(--highlight);
  border-radius: 4px;
}

/* ===== Architecture grid ===== */
.arch-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 20px;
  margin-top: 32px;
}
.arch-card {
  background: var(--bg-3);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 22px 24px;
}
.arch-card h3 {
  margin: 0 0 10px;
  color: var(--accent);
  font-size: 1.05rem;
  letter-spacing: 0.02em;
}
.arch-card .tech {
  margin: 12px 0 0;
  color: var(--muted);
  font-size: 12px;
  letter-spacing: 0.02em;
}

/* ===== Figures ===== */
.fig {
  margin: 28px 0;
  border: 1px solid var(--line);
  border-radius: 8px;
  overflow: hidden;
  background: var(--bg-2);
}
.fig img {
  display: block;
  width: 100%;
  height: auto;
}
.fig figcaption {
  padding: 14px 18px;
  color: var(--muted);
  font-size: 13px;
  border-top: 1px solid var(--line);
  background: var(--bg-3);
}
.fig.wide { max-width: 100%; }

.fig-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  margin: 0;
}
.fig-grid .fig { margin: 0; }
.fig-grid-6 {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 16px;
  margin: 16px 0 0;
}
.fig-grid-6 .fig { margin: 0; }
.fig-grid-6 figcaption {
  text-align: center;
  font-size: 12px;
  padding: 8px;
}

details.more {
  margin: 30px 0 0;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 14px 18px;
  background: var(--bg-2);
}
details.more summary {
  cursor: pointer;
  color: var(--accent);
  font-weight: 500;
  list-style: none;
}
details.more summary::before {
  content: "▸ ";
  display: inline-block;
  transition: transform 0.15s;
}
details.more[open] summary::before {
  transform: rotate(90deg);
}

/* ===== Code blocks (math/pseudocode) ===== */
pre.code-block {
  background: #0a0e14;
  border: 1px solid var(--line);
  border-left: 3px solid var(--accent-2);
  border-radius: 6px;
  padding: 18px 22px;
  overflow-x: auto;
  margin: 18px 0 22px;
  color: #c8d1da;
  font-family: "SF Mono", "JetBrains Mono", Menlo, Consolas, monospace;
  font-size: 13.5px;
  line-height: 1.55;
  letter-spacing: 0.01em;
}

/* ===== Mechanic lists (inside How-it-works) ===== */
ul.mech-list {
  margin: 18px 0;
  padding-left: 0;
  list-style: none;
}
ul.mech-list li {
  position: relative;
  padding: 12px 16px 12px 36px;
  margin-bottom: 10px;
  background: var(--bg-3);
  border: 1px solid var(--line);
  border-radius: 6px;
  color: #c8d1da;
}
ul.mech-list li::before {
  content: "▸";
  position: absolute;
  left: 14px;
  top: 12px;
  color: var(--accent);
  font-size: 14px;
}
ul.mech-list li strong { color: var(--text); }

/* ===== Method grid ===== */
.method-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 32px;
  margin-top: 32px;
}
.method-grid h3 {
  color: var(--accent-2);
  font-size: 1.05rem;
  margin: 0 0 12px;
}
.method-grid ul {
  list-style: none;
  padding: 0;
  margin: 0;
}
.method-grid ul li {
  padding: 6px 0;
  border-bottom: 1px dashed var(--line);
  color: #c8d1da;
}
.method-grid ul li:last-child { border-bottom: none; }
.method-grid ul.scn li strong { color: var(--highlight); }

/* ===== Findings ===== */
.finding {
  display: grid;
  grid-template-columns: 80px 1fr;
  gap: 30px;
  margin: 70px 0;
  align-items: start;
}
.finding-num {
  font-size: 3rem;
  font-weight: 700;
  color: var(--accent);
  letter-spacing: -0.04em;
  line-height: 1;
  opacity: 0.8;
}
.finding h3 { margin: 0 0 14px; font-size: 1.6rem; letter-spacing: -0.01em; }
.finding p { color: #c8d1da; margin: 0 0 14px; }
.hl {
  color: var(--highlight);
  font-weight: 700;
}
.finding-takeaway {
  background: rgba(63, 185, 80, 0.06);
  border-left: 3px solid var(--accent-2);
  padding: 14px 18px;
  border-radius: 4px;
  color: #d3e0d6 !important;
}

/* ===== Optimizer table ===== */
table.opt {
  width: 100%;
  border-collapse: collapse;
  margin: 24px 0;
  font-size: 14px;
  background: var(--bg-3);
  border: 1px solid var(--line);
  border-radius: 8px;
  overflow: hidden;
}
table.opt th, table.opt td {
  padding: 12px 16px;
  text-align: left;
  border-bottom: 1px solid var(--line);
}
table.opt th {
  background: var(--bg-2);
  color: var(--accent);
  font-weight: 600;
  font-size: 12px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}
table.opt td:nth-child(2) {
  color: var(--highlight);
  font-weight: 600;
  font-family: "SF Mono", "JetBrains Mono", Menlo, Consolas, monospace;
}
table.opt td:nth-child(3) {
  color: var(--muted);
  font-family: "SF Mono", "JetBrains Mono", Menlo, Consolas, monospace;
}
table.opt td:nth-child(4) { color: #c8d1da; font-size: 13px; }
table.opt tr:last-child td { border-bottom: none; }

/* ===== Callout ===== */
.callout {
  background: rgba(88, 166, 255, 0.05);
  border: 1px solid rgba(88, 166, 255, 0.25);
  border-radius: 8px;
  padding: 22px 26px;
  margin: 28px 0;
}
.callout h4 {
  margin: 0 0 12px;
  color: var(--accent);
  font-size: 1rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}
.callout ul {
  margin: 0 0 14px;
  padding-left: 22px;
  color: #c8d1da;
}
.callout p { margin: 0; color: #c8d1da; }

/* ===== Caveats ===== */
.caveats {
  list-style: none;
  padding: 0;
  margin: 24px 0 0;
  display: grid;
  gap: 14px;
}
.caveats li {
  background: var(--bg-3);
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 14px 18px;
  color: #c8d1da;
}
.caveats li strong { color: var(--warn); }

/* ===== Footer ===== */
.foot {
  border-top: 1px solid var(--line);
  padding: 36px 32px;
  text-align: center;
  color: var(--muted);
  font-size: 13px;
  background: var(--bg-2);
}
.foot .dim { color: #6a7280; font-size: 12px; margin-top: 6px; }
.foot p { margin: 0; }

/* ===== Responsive ===== */
@media (max-width: 800px) {
  .nav-links { display: none; }
  .nav-inner { padding: 12px 18px; }
  .hero { padding: 56px 18px 48px; }
  .hero h1 { font-size: clamp(1.7rem, 7vw, 2.4rem); margin-bottom: 18px; }
  .lede { font-size: 1.02rem; margin-bottom: 28px; }
  .section { padding: 48px 18px; }
  .section h2 { font-size: 1.5rem; }
  .section h3 { font-size: 1.15rem; }
  .section-lede { font-size: 0.98rem; }
  .hero-stats { grid-template-columns: 1fr 1fr; gap: 12px; }
  .hero-stats > div { padding: 14px 16px; }
  .stat-num { font-size: 1.5rem; }
  .finding { grid-template-columns: 1fr; gap: 12px; }
  .finding-num { font-size: 2rem; }
  .finding h3 { font-size: 1.25rem; }
  .fig-grid { grid-template-columns: 1fr; }
  .arch-grid { grid-template-columns: 1fr; gap: 14px; }
  .arch-card { padding: 16px 18px; }
  .big-quote { font-size: 1.1rem; padding: 16px 18px; }
  table { display: block; overflow-x: auto; -webkit-overflow-scrolling: touch; }
  pre { font-size: 12.5px; padding: 12px 14px; }
}
@media (max-width: 480px) {
  .hero-stats { grid-template-columns: 1fr; }
  .brand-sub { display: none; }
}