:root {
  --bg: #0a0f1e;
  --bg-elev-1: #0f1520;
  --bg-elev-2: #141b2e;

  --accent: #B1E74F;
  --accent-soft: rgba(177, 231, 79, 0.18);
  --accent-muted: rgba(177, 231, 79, 0.08);
  --accent-dim: rgba(177, 231, 79, 0.4);

  --fg: #f9fafb;
  --fg-2: #cbd5f5;
  --fg-3: #94a3b8;
  --fg-4: #64748b;

  --danger: #f87171;

  --border: rgba(148, 163, 184, 0.18);
  --border-strong: rgba(148, 163, 184, 0.35);

  --font-display: 'Outfit', 'Inter', sans-serif;
  --font-text: 'Inter', sans-serif;
  --font-mono: 'JetBrains Mono', monospace;

  --slide-h: 100vh;
  --slide-pad: clamp(3rem, 6vh, 6rem) clamp(3rem, 6vw, 8rem);
  --gap-xs: 0.75rem;
  --gap-sm: 1.25rem;
  --gap-md: 2rem;
  --gap-lg: 3.5rem;
  --gap-xl: 5rem;

  --stage-max: 1400px;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html, body { height: 100%; }

html { scroll-behavior: smooth; }

body {
  background: var(--bg);
  color: var(--fg);
  font-family: var(--font-text);
  font-size: 18px;
  line-height: 1.5;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

/* Slides — strict 100vh boxes, centered content */
.slide {
  height: var(--slide-h);
  padding: var(--slide-pad);
  display: grid;
  place-items: center;
  position: relative;
  overflow: hidden;
}

.stage {
  width: 100%;
  max-width: var(--stage-max);
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: var(--gap-md);
}

.stage.center { align-items: center; text-align: center; }

/* Slide number (subtle, bottom-left) */
.slide::after {
  content: attr(data-slide);
  position: absolute;
  left: clamp(1.5rem, 3vw, 3rem);
  bottom: clamp(1.5rem, 3vh, 3rem);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--fg-4);
  letter-spacing: 0.14em;
}

/* Brand mark (bottom-right on every slide except title & closing) */
.slide::before {
  content: "phail.ai";
  position: absolute;
  right: clamp(3rem, 5vw, 5rem);
  bottom: clamp(1.5rem, 3vh, 3rem);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--fg-4);
  letter-spacing: 0.14em;
}
.slide.title-slide::before,
.slide.closing-slide::before { display: none; }

/* Typography */
h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 700;
  line-height: 1.05;
  letter-spacing: -0.02em;
  color: var(--fg);
}

.kicker {
  font-family: var(--font-mono);
  text-transform: uppercase;
  font-weight: 600;
  font-size: 0.95rem;
  letter-spacing: 0.18em;
  color: var(--accent);
  display: inline-flex;
  align-items: center;
  gap: 0.75rem;
}
.kicker::before {
  content: "";
  width: 28px;
  height: 2px;
  background: var(--accent);
}

.eyebrow {
  color: var(--accent);
  font-weight: 500;
  font-size: 1.05rem;
  letter-spacing: 0.04em;
}

/* Navigation dots */
.navigation-dots {
  position: fixed;
  right: clamp(1rem, 1.5vw, 1.75rem);
  top: 50%;
  transform: translateY(-50%);
  display: flex;
  flex-direction: column;
  gap: 10px;
  z-index: 100;
}
.dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--fg-4);
  opacity: 0.4;
  transition: all 0.2s ease;
}
.dot:hover { opacity: 0.8; }
.dot.active {
  background: var(--accent);
  opacity: 1;
  transform: scale(1.4);
  box-shadow: 0 0 12px var(--accent-soft);
}

/* ==================== SLIDE 1: TITLE ==================== */
.title-slide {
  background:
    radial-gradient(ellipse at 70% 20%, var(--accent-muted), transparent 60%),
    radial-gradient(ellipse at 20% 80%, rgba(148, 163, 184, 0.05), transparent 50%),
    var(--bg);
}

.title-stage {
  display: grid;
  grid-template-rows: auto auto auto 1fr auto;
  gap: var(--gap-md);
  height: 100%;
  width: 100%;
  max-width: var(--stage-max);
  padding: clamp(2rem, 5vh, 4rem) 0;
}

.title-stage h1 {
  font-size: clamp(3.5rem, 7.5vw, 7rem);
  line-height: 0.95;
  max-width: 14ch;
}

.title-stage .deck {
  font-size: clamp(1.15rem, 1.6vw, 1.6rem);
  color: var(--fg-2);
  font-weight: 400;
  max-width: 52ch;
  line-height: 1.4;
}

.title-stage .footer {
  align-self: end;
  display: flex;
  justify-content: space-between;
  align-items: end;
  gap: var(--gap-lg);
  padding-top: var(--gap-md);
  border-top: 1px solid var(--border);
}

.title-stage .byline {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}
.title-stage .byline .name {
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--fg);
}
.title-stage .byline .role {
  color: var(--fg-3);
  font-size: 0.95rem;
}

.title-stage .url {
  font-family: var(--font-mono);
  color: var(--accent);
  font-size: 1.15rem;
  letter-spacing: 0.04em;
}

/* ==================== SLIDE 2: BIG QUESTION ==================== */
.big-question h1 {
  font-size: clamp(3rem, 6.5vw, 6rem);
  line-height: 1.05;
  font-weight: 600;
  max-width: 20ch;
}
.big-question .subline {
  margin-top: var(--gap-lg);
  font-family: var(--font-display);
  font-size: clamp(2.5rem, 4.5vw, 4rem);
  color: var(--accent);
  font-weight: 600;
  max-width: 28ch;
  line-height: 1.15;
  letter-spacing: -0.01em;
}

/* ==================== SLIDE 3: PROBLEM ==================== */
.problem-stage h2 {
  font-size: clamp(2.5rem, 4.5vw, 4rem);
  max-width: 22ch;
}
.problem-stage .sub {
  color: var(--fg-3);
  font-size: 1.15rem;
  max-width: 60ch;
}

.problem-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--gap-sm);
  width: 100%;
  margin-top: var(--gap-md);
}
.problem-item {
  display: flex;
  gap: 1.25rem;
  padding: 1.5rem 1.75rem;
  background: var(--bg-elev-1);
  border: 1px solid var(--border);
  border-radius: 14px;
  align-items: baseline;
}
.problem-item .idx {
  font-family: var(--font-mono);
  color: var(--accent);
  font-size: 0.8rem;
  letter-spacing: 0.1em;
  min-width: 2ch;
}
.problem-item .text {
  font-size: 1.3rem;
  color: var(--fg);
  font-weight: 500;
  line-height: 1.35;
}

/* ==================== SLIDE 4: PRINCIPLES ==================== */
.principles-stage h2 {
  font-size: clamp(2.5rem, 4.5vw, 4rem);
  max-width: 20ch;
}
.principles-stage .sub {
  color: var(--fg-3);
  font-size: 1.15rem;
}

.principles {
  display: flex;
  flex-direction: column;
  gap: 0.85rem;
  width: 100%;
  max-width: 860px;
  margin: var(--gap-md) auto 0;
}

.principle {
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) auto minmax(0, 1fr);
  gap: 2.5rem;
  align-items: center;
  padding: 1.35rem 2rem;
  background: var(--bg-elev-1);
  border: 1px solid var(--border);
  border-radius: 14px;
}
.principle .mech {
  font-family: var(--font-display);
  font-size: 1.6rem;
  font-weight: 600;
  color: var(--fg);
  text-align: right;
  line-height: 1.2;
}
.principle .arrow {
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: 1.75rem;
  line-height: 1;
}
.principle .conseq {
  font-size: 1.2rem;
  color: var(--fg-2);
  line-height: 1.35;
}

/* ==================== SLIDE 5: BRIDGE ==================== */
.bridge-stage {
  align-items: center;
  text-align: center;
}
.bridge-stage h2 {
  font-size: clamp(2.25rem, 4vw, 3.5rem);
}
.bridge-stage .sub {
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: 1rem;
  letter-spacing: 0.08em;
}
.screenshot-frame {
  position: relative;
  max-width: min(1200px, 100%);
  max-height: 62vh;
  border-radius: 14px;
  overflow: hidden;
  border: 1px solid var(--accent-dim);
  box-shadow:
    0 30px 80px rgba(0, 0, 0, 0.6),
    0 0 60px var(--accent-muted);
  display: inline-block;
}
.screenshot-frame img {
  display: block;
  max-width: 100%;
  max-height: 62vh;
  width: auto;
  height: auto;
}
.screenshot-frame.interactive {
  cursor: pointer;
  text-decoration: none;
  transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
}
.screenshot-frame.interactive:hover {
  transform: translateY(-8px);
  border-color: var(--accent);
  box-shadow:
    0 50px 100px rgba(0, 0, 0, 0.7),
    0 0 100px var(--accent-soft);
}
.screenshot-frame.interactive:hover .open-hint {
  background: rgba(177, 231, 79, 0.18);
}
.screenshot-frame .open-hint {
  position: absolute;
  bottom: 1rem;
  right: 1rem;
  background: rgba(10, 15, 30, 0.85);
  border: 1px solid var(--accent);
  padding: 0.55rem 0.95rem;
  border-radius: 999px;
  font-family: var(--font-mono);
  color: var(--accent);
  font-size: 0.85rem;
  letter-spacing: 0.08em;
  pointer-events: none;
  backdrop-filter: blur(6px);
}

/* ==================== SLIDE 6: LIVE DEMO ==================== */
.demo-stage {
  align-items: center;
  text-align: center;
  gap: var(--gap-lg);
}
.demo-stage h2 {
  font-size: clamp(2.5rem, 4.5vw, 4rem);
}
.demo-stage .sub { color: var(--fg-3); font-size: 1.2rem; }

.demo-card {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 1.25rem;
  padding: clamp(2.5rem, 5vh, 4rem) clamp(3rem, 6vw, 6rem);
  border-radius: 20px;
  background:
    radial-gradient(circle at 50% 0%, var(--accent-muted), transparent 70%),
    var(--bg-elev-2);
  border: 1px solid var(--accent);
  text-decoration: none;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  box-shadow: 0 0 40px var(--accent-muted);
}
.demo-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 0 60px var(--accent-soft);
}
.demo-card .label {
  font-family: var(--font-mono);
  color: var(--accent);
  font-size: 0.75rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
}
.demo-card .url {
  font-family: var(--font-mono);
  font-size: clamp(2rem, 4vw, 3.25rem);
  color: var(--fg);
  font-weight: 600;
  letter-spacing: 0.02em;
}

.demo-chips {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.75rem;
  max-width: 1200px;
  width: 100%;
}
.demo-chips.three { grid-template-columns: repeat(3, 1fr); max-width: 960px; }
.demo-chip {
  background: var(--bg-elev-1);
  padding: 1rem 1.25rem;
  border-radius: 10px;
  border: 1px solid var(--border);
  text-align: left;
}
.demo-chip .k {
  display: block;
  color: var(--fg-4);
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  margin-bottom: 0.35rem;
}
.demo-chip .v {
  color: var(--accent);
  font-family: var(--font-display);
  font-size: 1.05rem;
  font-weight: 600;
}

/* ==================== SLIDE 7: RESULTS ==================== */
.results-stage h2 {
  font-size: clamp(2.5rem, 4.5vw, 4rem);
  max-width: 20ch;
}
.results-stage .sub { color: var(--fg-3); font-size: 1.15rem; }

.stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
  width: 100%;
  margin-top: var(--gap-md);
}
.stat {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  padding: 2.5rem 2rem;
  background: var(--bg-elev-1);
  border: 1px solid var(--border);
  border-radius: 16px;
  min-height: 260px;
  justify-content: space-between;
}
.stat .num {
  font-family: var(--font-display);
  font-size: clamp(3rem, 5.5vw, 4.5rem);
  font-weight: 700;
  color: var(--accent);
  line-height: 1;
  letter-spacing: -0.03em;
}
.stat .label {
  font-size: 1.15rem;
  color: var(--fg);
  font-weight: 500;
  line-height: 1.35;
}
.stat .label em {
  font-style: normal;
  color: var(--accent);
  font-weight: 600;
}
.stat .note {
  color: var(--fg-4);
  font-size: 0.9rem;
  font-family: var(--font-mono);
  letter-spacing: 0.04em;
}
.stat.punch {
  border-color: var(--accent);
  background:
    radial-gradient(ellipse at top right, var(--accent-muted), transparent 70%),
    var(--bg-elev-2);
  box-shadow: 0 0 40px var(--accent-muted);
}

/* ==================== SLIDE 8: WHAT'S NEXT ==================== */
.next-stage h2 {
  font-size: clamp(2.5rem, 4.5vw, 4rem);
}
.next-stage .sub { color: var(--fg-3); font-size: 1.15rem; }

.next-list {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  width: 100%;
  margin-top: var(--gap-md);
}
.next-item {
  display: grid;
  grid-template-columns: minmax(200px, 280px) 1fr;
  gap: 2.5rem;
  align-items: center;
  padding: 1.5rem 2rem;
  background: var(--bg-elev-1);
  border: 1px solid var(--border);
  border-left: 3px solid var(--accent);
  border-radius: 12px;
}
.next-item .label {
  font-family: var(--font-display);
  font-size: 1.6rem;
  color: var(--fg);
  font-weight: 600;
}
.next-item .detail {
  color: var(--fg-2);
  font-size: 1.1rem;
  line-height: 1.4;
}
.next-item.cta {
  border: 1px solid var(--accent);
  border-left: 3px solid var(--accent);
  background:
    radial-gradient(ellipse at top right, var(--accent-muted), transparent 70%),
    var(--bg-elev-2);
  box-shadow: 0 0 40px var(--accent-muted);
}
.next-item.cta .label { color: var(--accent); font-size: 1.85rem; }
.next-item.cta .detail { color: var(--fg); font-size: 1.2rem; }
.next-item.cta .detail strong { color: var(--accent); font-weight: 600; }

/* ==================== SLIDE 9: CLOSING ==================== */
.closing-slide {
  background:
    radial-gradient(ellipse at 50% 0%, var(--accent-muted), transparent 60%),
    var(--bg);
}
.closing-stage {
  align-items: center;
  text-align: center;
  gap: var(--gap-md);
}
.closing-stage h1 {
  font-size: clamp(3rem, 6vw, 5.5rem);
  max-width: 20ch;
  font-weight: 600;
}
.closing-stage .answer {
  font-size: clamp(1.5rem, 2.4vw, 2.25rem);
  color: var(--accent);
  font-weight: 500;
}
.closing-stage .url {
  display: inline-block;
  margin-top: var(--gap-md);
  padding: 0.9rem 1.6rem;
  border: 1px solid var(--accent);
  border-radius: 999px;
  font-family: var(--font-mono);
  font-size: 1.15rem;
  color: var(--accent);
  text-decoration: none;
  letter-spacing: 0.04em;
  transition: background 0.2s ease;
}
.closing-stage .url:hover { background: var(--accent-muted); }
.closing-stage .contact {
  margin-top: var(--gap-md);
  color: var(--fg-3);
  font-size: 1rem;
}

/* ==================== RESPONSIVE ==================== */
@media (max-width: 1100px) {
  :root { --slide-pad: clamp(2rem, 5vh, 4rem) clamp(1.5rem, 5vw, 3rem); }

  .problem-grid { grid-template-columns: 1fr; }

  .principle {
    grid-template-columns: 1fr;
    gap: 0.5rem;
    padding: 1.1rem 1.25rem;
    text-align: center;
  }
  .principle .mech { text-align: center; font-size: 1.25rem; }
  .principle .arrow { font-size: 1.25rem; }
  .principle .conseq { font-size: 1rem; }

  .stats { grid-template-columns: 1fr; gap: 0.75rem; }
  .stat { min-height: 0; padding: 1.5rem; }
  .stat .num { font-size: 2.5rem; }

  .demo-chips, .demo-chips.three { grid-template-columns: 1fr 1fr; }

  .next-item { grid-template-columns: 1fr; gap: 0.25rem; padding: 1.25rem; }

  .title-stage .footer { flex-direction: column; align-items: flex-start; gap: 1rem; }

  .navigation-dots { display: none; }
}

/* ==================== MOBILE ==================== */
@media (max-width: 768px) {
  :root {
    --slide-pad: 2.5rem 1.25rem;
    --gap-md: 1.25rem;
    --gap-lg: 2rem;
  }

  body { font-size: 16px; }

  /* Let slides grow with content; they'd otherwise clip on phones */
  .slide {
    height: auto;
    min-height: 100vh;
    overflow: visible;
    padding-bottom: 4.5rem;
  }
  .stage { gap: var(--gap-sm); }

  .slide::after,
  .slide::before {
    bottom: 1.25rem;
    font-size: 0.7rem;
  }
  .slide::after { left: 1.25rem; }
  .slide::before { right: 1.25rem; }

  .kicker { font-size: 0.78rem; letter-spacing: 0.14em; gap: 0.55rem; }
  .kicker::before { width: 20px; }

  /* Title */
  .title-stage { gap: 1.25rem; padding: 1.5rem 0 0; }
  .title-stage h1 { font-size: clamp(2.25rem, 9.5vw, 3.5rem); max-width: 16ch; }
  .title-stage .deck { font-size: 1.05rem; line-height: 1.4; }
  .title-stage .byline .name { font-size: 1.05rem; }
  .title-stage .byline .role { font-size: 0.85rem; }
  .title-stage .url { font-size: 1rem; }

  /* Big question */
  .big-question h1 { font-size: clamp(1.85rem, 8vw, 2.75rem); }
  .big-question .subline {
    font-size: clamp(1.5rem, 6.5vw, 2.25rem);
    margin-top: var(--gap-md);
  }

  /* Section headlines */
  .problem-stage h2,
  .principles-stage h2,
  .results-stage h2,
  .next-stage h2,
  .demo-stage h2,
  .bridge-stage h2 {
    font-size: clamp(1.5rem, 6.5vw, 2.15rem);
    line-height: 1.1;
  }
  .problem-stage .sub,
  .principles-stage .sub,
  .results-stage .sub,
  .next-stage .sub,
  .demo-stage .sub,
  .bridge-stage .sub {
    font-size: 0.95rem;
    line-height: 1.4;
  }

  /* Problem cards */
  .problem-grid { gap: 0.6rem; margin-top: 0.5rem; }
  .problem-item { padding: 0.95rem 1.1rem; gap: 0.85rem; }
  .problem-item .idx { font-size: 0.7rem; }
  .problem-item .text { font-size: 1rem; line-height: 1.3; }

  /* Principles */
  .principles { gap: 0.5rem; margin-top: 0.5rem; }
  .principle { padding: 0.85rem 1rem; }
  .principle .mech { font-size: 1.05rem; }
  .principle .arrow { font-size: 1rem; }
  .principle .conseq { font-size: 0.95rem; }

  /* Bridge screenshot */
  .bridge-stage { gap: 1rem; }
  .screenshot-frame { max-height: 55vh; }
  .screenshot-frame img { max-height: 55vh; }

  /* Demo */
  .demo-stage { gap: var(--gap-md); }
  .demo-card {
    padding: 1.75rem 2.25rem;
    gap: 0.75rem;
  }
  .demo-card .url { font-size: 1.6rem; }
  .demo-chips, .demo-chips.three {
    grid-template-columns: 1fr;
    gap: 0.5rem;
  }
  .demo-chip { padding: 0.75rem 0.95rem; }
  .demo-chip .v { font-size: 0.95rem; }

  /* Stats */
  .stats { margin-top: 0.5rem; gap: 0.6rem; }
  .stat { padding: 1.1rem 1.2rem; gap: 0.45rem; }
  .stat .num { font-size: 2rem; }
  .stat .label { font-size: 0.95rem; }
  .stat .note { font-size: 0.78rem; }

  /* Next */
  .next-list { gap: 0.6rem; margin-top: 0.5rem; }
  .next-item { padding: 0.95rem 1.1rem; }
  .next-item .label { font-size: 1.15rem; }
  .next-item .detail { font-size: 0.95rem; }
  .next-item.cta .label { font-size: 1.3rem; }
  .next-item.cta .detail { font-size: 1rem; }

  /* Closing */
  .closing-stage h1 { font-size: clamp(2rem, 9vw, 3rem); }
  .closing-stage .answer { font-size: 1.25rem; }
  .closing-stage .url { font-size: 0.95rem; padding: 0.7rem 1.25rem; }
  .closing-stage .contact { font-size: 0.85rem; }
}