:root {
  --bg: #0a0b0f;
  --bg-2: #0f1117;
  --ink: #eef1f6;
  --muted: #9aa3b2;
  --faint: #5b6473;
  --accent: #6ee7ff; /* cyan */
  --accent-2: #a78bfa; /* violet */
  --accent-3: #f472b6; /* pink */
  --good: #34d399;
  --warn: #fbbf24;
  --line: rgba(255, 255, 255, 0.08);
  --card: rgba(255, 255, 255, 0.035);
  --card-line: rgba(255, 255, 255, 0.09);
}

.reveal {
  font-family:
    "Inter",
    system-ui,
    -apple-system,
    sans-serif;
  font-size: 32px;
  color: var(--ink);
  font-weight: 400;
}

/* ---------- background ---------- */
.reveal-viewport {
  background:
    radial-gradient(
      900px 600px at 12% -10%,
      rgba(110, 231, 255, 0.1),
      transparent 60%
    ),
    radial-gradient(
      900px 700px at 100% 110%,
      rgba(167, 139, 250, 0.12),
      transparent 55%
    ),
    var(--bg);
}

/* ---------- typography ---------- */
.reveal h1,
.reveal h2,
.reveal h3 {
  font-family: "Inter", sans-serif;
  color: var(--ink);
  text-transform: none;
  letter-spacing: -0.02em;
  line-height: 1.08;
  margin: 0 0 0.35em;
  font-weight: 800;
  text-shadow: none;
}
.reveal h1 {
  font-size: 2.45em;
  font-weight: 900;
}
.reveal h2 {
  font-size: 1.65em;
}
.reveal h3 {
  font-size: 1.15em;
  font-weight: 700;
}
.reveal p {
  line-height: 1.45;
}

.reveal section {
  text-align: left;
}
.reveal .slides section .fragment.fade-in-then-semi-out.visible {
  opacity: 1;
}

/* ---------- helpers ---------- */
.grad {
  background: linear-gradient(
    100deg,
    var(--accent),
    var(--accent-2) 55%,
    var(--accent-3)
  );
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}
.muted {
  color: var(--muted);
}
.faint {
  color: var(--faint);
}
.accent {
  color: var(--accent);
}
.center {
  text-align: center;
}
.mono {
  font-family: "JetBrains Mono", monospace;
}
.small {
  font-size: 0.72em;
}
.tiny {
  font-size: 0.58em;
}
.lead {
  font-size: 1.15em;
  color: var(--muted);
  line-height: 1.5;
}
.nowrap {
  white-space: nowrap;
}

.kicker {
  font-family: "JetBrains Mono", monospace;
  font-size: 0.55em;
  letter-spacing: 0.28em;
  text-transform: uppercase;
  color: var(--accent);
  font-weight: 500;
  margin-bottom: 0.9em;
}

.pill {
  display: inline-block;
  font-family: "JetBrains Mono", monospace;
  font-size: 0.5em;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  padding: 0.45em 0.9em;
  border: 1px solid var(--card-line);
  border-radius: 999px;
  color: var(--muted);
  background: var(--card);
  margin: 0.2em 0.3em 0.2em 0;
}

.rule {
  height: 4px;
  width: 70px;
  border-radius: 4px;
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
  margin: 0.2em 0 0.9em;
}

/* ---------- cards / columns ---------- */
.cols {
  display: grid;
  gap: 0.7em;
}
.cols.two {
  grid-template-columns: 1fr 1fr;
}
.cols.three {
  grid-template-columns: repeat(3, 1fr);
}

.card {
  background: var(--card);
  border: 1px solid var(--card-line);
  border-radius: 16px;
  padding: 0.85em 0.95em;
}
.card h3 {
  margin-bottom: 0.25em;
}
.card p {
  margin: 0;
  font-size: 0.78em;
  color: var(--muted);
  line-height: 1.4;
}

.card.is {
  border-color: rgba(52, 211, 153, 0.35);
}
.card.is .tag {
  color: var(--good);
}
.card.isnt {
  border-color: rgba(244, 114, 182, 0.32);
}
.card.isnt .tag {
  color: var(--accent-3);
}
.tag {
  font-family: "JetBrains Mono", monospace;
  font-size: 0.52em;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  display: block;
  margin-bottom: 0.5em;
}

/* ---------- lists ---------- */
.reveal ul {
  list-style: none;
  margin-left: 0;
}
.reveal ul li {
  position: relative;
  padding-left: 1.1em;
  margin: 0.5em 0;
  line-height: 1.4;
}
.reveal ul li::before {
  content: "›";
  position: absolute;
  left: 0;
  color: var(--accent);
  font-weight: 700;
}
.reveal .clean li::before {
  content: "";
}
.reveal .clean li {
  padding-left: 0;
}

.check li::before {
  content: "✓";
  color: var(--good);
}
.cross li::before {
  content: "✕";
  color: var(--accent-3);
}

/* ---------- footer / numbers ---------- */
.reveal .slide-number {
  font-family: "JetBrains Mono", monospace;
  font-size: 14px;
  color: var(--faint);
  background: transparent;
  right: auto;
  left: 22px;
  bottom: 16px;
}

.reveal .progress {
  color: var(--accent);
  height: 3px;
}

/* nav arrows: own corner, accent colored, more breathing room */
.reveal .controls {
  right: 18px;
  bottom: 12px;
  color: var(--muted);
}
.reveal .controls button {
  color: var(--muted);
}
.reveal .controls .navigate-left {
  right: 4.2em;
}
.reveal .controls .navigate-right {
  right: 0.6em;
}
.reveal .controls button.highlight,
.reveal .controls button:hover {
  color: var(--accent);
}

/* big quote / statement slide */
.statement {
  font-size: 1.9em;
  font-weight: 800;
  line-height: 1.18;
  letter-spacing: -0.02em;
}

/* mental model diagram */
.flow {
  display: flex;
  align-items: stretch;
  gap: 0.55em;
  margin-top: 0.5em;
}
.flow .step {
  flex: 1;
  background: var(--card);
  border: 1px solid var(--card-line);
  border-radius: 14px;
  padding: 0.7em 0.6em;
  text-align: center;
}
.flow .step .n {
  font-family: "JetBrains Mono", monospace;
  color: var(--accent);
  font-size: 0.6em;
  letter-spacing: 0.1em;
}
.flow .step h3 {
  font-size: 0.85em;
  margin: 0.25em 0 0.15em;
}
.flow .step p {
  font-size: 0.6em;
  color: var(--muted);
  margin: 0;
  line-height: 1.35;
}
.flow .arrow {
  display: flex;
  align-items: center;
  color: var(--faint);
  font-size: 1.1em;
}

/* ---------- milestone cards ---------- */
.milestones {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.7em;
  margin-top: 0.6em;
}
.ms {
  position: relative;
  background: var(--card);
  border: 1px solid var(--card-line);
  border-radius: 16px;
  padding: 0.8em 0.9em 0.8em 1.05em;
  overflow: hidden;
}
/* colored accent bar on the left edge */
.ms::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 4px;
  background: var(--c, var(--accent));
}
.ms .yr {
  font-family: "JetBrains Mono", monospace;
  font-weight: 700;
  font-size: 0.78em;
  color: var(--c, var(--accent));
  letter-spacing: 0.04em;
}
.ms h3 {
  font-size: 0.9em;
  margin: 0.1em 0 0.26em;
  color: var(--ink);
}
.ms p {
  font-size: 0.71em;
  color: var(--muted);
  line-height: 1.4;
  margin: 0;
}
.ms p em {
  color: var(--ink);
  font-weight: 700;
}
/* hero — the Transformer */
.ms.hero {
  border-color: rgba(167, 139, 250, 0.45);
  background: linear-gradient(
    120deg,
    rgba(167, 139, 250, 0.16),
    var(--card) 70%
  );
  box-shadow: 0 0 30px -10px rgba(167, 139, 250, 0.7);
}
/* now — you are here */
.ms.now {
  border-color: rgba(244, 114, 182, 0.45);
}
.ms.now .yr {
  animation: glow 2s infinite;
}
@keyframes glow {
  0%,
  100% {
    opacity: 1;
  }
  50% {
    opacity: 0.5;
  }
}

.reveal a {
  color: var(--accent);
  text-decoration: none;
}
.reveal em {
  color: var(--ink);
  font-style: normal;
  font-weight: 700;
}
.reveal strong {
  color: var(--ink);
  font-weight: 700;
}

.titlewrap {
  padding-left: 6%;
}

/* ---------- math (KaTeX) ---------- */
/* keep typeset equations left-aligned and tight inside cards */
.reveal .katex-display {
  margin: 0.35em 0;
  text-align: left;
}
.reveal .katex {
  color: var(--ink);
  font-size: 1em;
}
/* small typeset-math label used in place of a .tag */
.mathtag {
  display: block;
  margin-bottom: 0.45em;
  color: var(--accent-2);
}
.mathtag .katex {
  color: inherit;
  font-size: 1.1em;
}

/* box to hold one or more typeset equations */
.mathbox {
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--card-line);
  border-left: 3px solid var(--c, var(--accent));
  border-radius: 10px;
  padding: 0.45em 0.85em;
}
.mathbox.center .katex-display {
  text-align: center;
}

/* ---------- deep-dive helpers ---------- */
/* formula / definition box */
.eq {
  font-family: "JetBrains Mono", monospace;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--card-line);
  border-left: 3px solid var(--c, var(--accent));
  border-radius: 10px;
  padding: 0.6em 0.85em;
  font-size: 0.72em;
  color: var(--ink);
  line-height: 1.55;
}
.eq .cmt {
  color: var(--faint);
}

/* big statistic */
.bignum {
  font-family: "JetBrains Mono", monospace;
  font-weight: 700;
  font-size: 2.1em;
  line-height: 1;
  color: var(--c, var(--accent));
  letter-spacing: -0.02em;
}
.bignum .unit {
  font-size: 0.38em;
  color: var(--muted);
  letter-spacing: 0;
}

/* example / highlight box */
.exbox {
  background: linear-gradient(
    120deg,
    rgba(110, 231, 255, 0.08),
    transparent 80%
  );
  border: 1px solid var(--card-line);
  border-radius: 14px;
  padding: 0.7em 0.95em;
  font-size: 0.86em;
  line-height: 1.5;
}
.exbox .hl {
  color: var(--accent);
  font-weight: 700;
}
.exbox .hl2 {
  color: var(--accent-3);
  font-weight: 700;
}

/* scale escalation cards */
.scale {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.7em;
  align-items: end;
  margin-top: 0.6em;
}
.scale .step {
  background: var(--card);
  border: 1px solid var(--card-line);
  border-radius: 14px;
  padding: 0.7em 0.8em;
}
.scale .step .lbl {
  font-family: "JetBrains Mono", monospace;
  font-size: 0.62em;
  letter-spacing: 0.08em;
  color: var(--muted);
}
.scale .step .val {
  font-family: "JetBrains Mono", monospace;
  font-weight: 700;
  font-size: 1.3em;
  color: var(--c, var(--accent));
}

/* truth table */
.ttable {
  border-collapse: collapse;
  font-family: "JetBrains Mono", monospace;
  font-size: 0.74em;
}
.ttable th,
.ttable td {
  border: 1px solid var(--card-line);
  padding: 0.32em 0.85em;
  text-align: center;
}
.ttable th {
  color: var(--muted);
  font-weight: 700;
  background: rgba(255, 255, 255, 0.03);
}
.ttable td.out1 {
  color: var(--accent);
  font-weight: 700;
}
.ttable td.out0 {
  color: var(--accent-3);
  font-weight: 700;
}

/* XOR scatter plot */
.xorplot {
  position: relative;
  width: 210px;
  height: 210px;
  margin: 0.2em auto 32px;
  border-left: 2px solid var(--card-line);
  border-bottom: 2px solid var(--card-line);
}
/* a sample straight line that fails to separate the classes */
.xorplot::after {
  content: "";
  position: absolute;
  left: -6%;
  right: -6%;
  top: 50%;
  height: 2px;
  background: repeating-linear-gradient(
    90deg,
    var(--faint) 0 8px,
    transparent 8px 14px
  );
  transform: rotate(-32deg);
}
.xorplot .pt {
  position: absolute;
  width: 34px;
  height: 34px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: "JetBrains Mono", monospace;
  font-size: 13px;
  font-weight: 700;
  transform: translate(-50%, 50%);
  z-index: 2;
}
.xorplot .pt.one {
  background: rgba(110, 231, 255, 0.16);
  border: 2px solid var(--accent);
  color: var(--accent);
}
.xorplot .pt.zero {
  background: rgba(244, 114, 182, 0.14);
  border: 2px solid var(--accent-3);
  color: var(--accent-3);
}
.xorplot .axlbl {
  position: absolute;
  font-family: "JetBrains Mono", monospace;
  font-size: 11px;
  color: var(--faint);
}

/* mini neural-net layer diagram */
.net {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1.4em;
  margin: 0.7em 0;
}
.net .layer {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5em;
}
.net .node {
  width: 26px;
  height: 26px;
  border-radius: 50%;
  border: 2px solid var(--c, var(--accent));
  background: rgba(110, 231, 255, 0.08);
  box-shadow: 0 0 10px -3px var(--c, var(--accent));
}
.net .cap {
  text-align: center;
  font-family: "JetBrains Mono", monospace;
  font-size: 0.5em;
  color: var(--faint);
  margin-top: 0.5em;
  letter-spacing: 0.06em;
}
.net .arrows {
  color: var(--faint);
  font-size: 1.3em;
}

/* ---------- model-history tour: animated timeline ---------- */
.tl {
  margin-top: 0.45em;
  border-left: 2px solid var(--card-line);
  padding-left: 1.1em;
}
.tl-row {
  display: flex;
  align-items: baseline;
  gap: 0.7em;
  padding: 0.16em 0;
  position: relative;
  opacity: 0; /* revealed by the cascade once the slide is present */
}
/* dot on the rail */
.tl-row::before {
  content: "";
  position: absolute;
  left: calc(-1.1em - 6px);
  top: 0.6em;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--c, var(--accent));
  box-shadow: 0 0 9px -1px var(--c, var(--accent));
}
.tl-yr {
  font-family: "JetBrains Mono", monospace;
  font-weight: 700;
  font-size: 0.72em;
  color: var(--c, var(--accent));
  min-width: 2.7em;
  flex-shrink: 0;
}
.tl-row h3 {
  font-size: 0.8em;
  margin: 0;
  white-space: nowrap;
  flex-shrink: 0;
}
.tl-row p {
  font-size: 0.66em;
  color: var(--muted);
  margin: 0;
  line-height: 1.3;
}
.tl-row .dash {
  color: var(--faint);
  font-size: 0.66em;
}

/* auto-cascade: rows slide/fade in once the slide is on screen */
.reveal section.present .tl-row {
  animation: tlIn 0.45s cubic-bezier(0.2, 0.7, 0.3, 1) both;
  animation-delay: calc(var(--i, 0) * 0.06s);
}
@keyframes tlIn {
  from {
    opacity: 0;
    transform: translateY(11px);
  }
  to {
    opacity: 1;
    transform: none;
  }
}

/* ---------- tour overview: four-era map ---------- */
.cols.four {
  grid-template-columns: repeat(4, 1fr);
  gap: 0.6em;
}
.eracard {
  padding: 0.7em 0.7em 0.75em;
  border-top: 3px solid var(--c, var(--accent));
  opacity: 0;
}
.reveal section.present .eracard {
  animation: tlIn 0.5s cubic-bezier(0.2, 0.7, 0.3, 1) both;
  animation-delay: calc(var(--i, 0) * 0.12s);
}
.eracard .tag {
  color: var(--c, var(--accent));
}
.eralist {
  list-style: none;
  margin: 0.2em 0 0;
  padding: 0;
}
.eralist li {
  padding: 0;
  margin: 0.16em 0;
  font-size: 0.62em;
  line-height: 1.25;
}
.eralist li::before {
  content: "";
}
.eralist .y {
  font-family: "JetBrains Mono", monospace;
  color: var(--c, var(--accent));
  margin-right: 0.45em;
}