:root {
  --ink: #18212f;
  --muted: #667085;
  --line: #d9e0ea;
  --surface: #ffffff;
  --soft: #f5f7f9;
  --green: #0f766e;
  --red: #b42318;
  --gold: #b7791f;
  --blue: #2f5f98;
  --slate: #243447;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  color: var(--ink);
  background:
    radial-gradient(circle at top left, rgba(15, 118, 110, .16), transparent 34rem),
    linear-gradient(180deg, #eef2f5, #f8fafc 55%, #eef2f5);
  font-family: Charter, Georgia, "Times New Roman", serif;
}
a { color: var(--green); }
button, textarea {
  font: 700 14px/1.2 Avenir, "Trebuchet MS", sans-serif;
}
.site-hero {
  background:
    linear-gradient(90deg, rgba(24,33,47,.9), rgba(15,118,110,.7)),
    repeating-linear-gradient(135deg, #17202d 0 18px, #1d2a38 18px 36px);
  color: white;
  min-height: 44vh;
  padding: 34px max(28px, calc((100vw - 1180px) / 2)) 88px;
}
.site-hero nav {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content: flex-end;
  margin-bottom: 46px;
}
.site-hero nav a {
  color: white;
  border: 1px solid rgba(255,255,255,.32);
  border-radius: 999px;
  padding: 8px 13px;
  text-decoration: none;
  font: 700 13px/1 Avenir, "Trebuchet MS", sans-serif;
}
.site-hero p,
.lesson-rail > p {
  margin: 0 0 12px;
  font: 700 13px/1.2 Avenir, "Trebuchet MS", sans-serif;
  letter-spacing: .08em;
  text-transform: uppercase;
}
.site-hero h1 {
  font-size: clamp(40px, 7vw, 84px);
  line-height: .98;
  max-width: 920px;
  margin: 0 0 24px;
}
.site-hero span {
  display: block;
  max-width: 760px;
  font: 22px/1.45 Avenir, "Trebuchet MS", sans-serif;
}
.site-hero .hero-summary {
  max-width: 890px;
}
.hero-briefs {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
  max-width: 1080px;
  margin-top: 30px;
}
.hero-briefs span {
  max-width: none;
  min-height: 128px;
  padding: 16px;
  color: rgba(255,255,255,.92);
  background: rgba(255,255,255,.1);
  border: 1px solid rgba(255,255,255,.24);
  border-radius: 8px;
  font: 15px/1.45 Avenir, "Trebuchet MS", sans-serif;
}
.hero-briefs strong {
  display: block;
  margin-bottom: 8px;
  color: white;
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: .08em;
}
main {
  width: min(1180px, calc(100vw - 40px));
  margin: 0 auto;
}
.part-band {
  display: grid;
  grid-template-columns: minmax(220px, 310px) 1fr;
  gap: 28px;
  padding: 34px 0;
  border-bottom: 1px solid var(--line);
}
.part-copy h2 {
  margin: 0 0 10px;
  font-size: 30px;
}
.part-copy span,
.topic-card span,
.lesson-rail span {
  color: var(--muted);
  line-height: 1.45;
}
.topic-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 12px;
}
.topic-card {
  display: grid;
  gap: 8px;
  min-height: 160px;
  padding: 18px;
  background: rgba(255,255,255,.9);
  border: 1px solid var(--line);
  border-radius: 8px;
  color: var(--ink);
  text-decoration: none;
  box-shadow: 0 12px 28px rgba(36, 52, 71, .08);
}
.topic-card strong { font-size: 18px; }
.topic-card small {
  align-self: end;
  color: var(--blue);
  font: 700 12px/1.2 Avenir, "Trebuchet MS", sans-serif;
  text-transform: uppercase;
}
.lesson-topbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 16px max(20px, calc((100vw - 1320px) / 2));
  color: white;
  background: var(--slate);
  font: 700 13px/1.2 Avenir, "Trebuchet MS", sans-serif;
}
.lesson-topbar a { color: white; text-decoration: none; }
.lesson-shell {
  width: min(1320px, calc(100vw - 28px));
  display: grid;
  grid-template-columns: 330px minmax(0, 1fr);
  gap: 20px;
  padding: 20px 0 42px;
}
.lesson-rail {
  position: sticky;
  top: 16px;
  align-self: start;
  max-height: calc(100vh - 32px);
  overflow: auto;
  padding: 22px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 14px;
  box-shadow: 0 16px 36px rgba(36, 52, 71, .1);
}
.lesson-rail h1 {
  margin: 0 0 10px;
  font-size: 28px;
  line-height: 1.05;
}
.lesson-meta {
  display: grid;
  gap: 9px;
  margin: 20px 0;
  padding: 14px;
  background: var(--soft);
  border-radius: 12px;
  font: 700 13px/1.25 Avenir, "Trebuchet MS", sans-serif;
}
.lesson-meta audio {
  width: 100%;
}
.pending { color: var(--muted); }
.slide-list {
  display: grid;
  gap: 8px;
}
.slide-jump {
  display: grid;
  grid-template-columns: 42px 1fr;
  gap: 8px;
  width: 100%;
  text-align: left;
  padding: 11px 12px;
  color: var(--ink);
  background: white;
  border: 1px solid var(--line);
  border-radius: 10px;
  cursor: pointer;
}
.slide-jump.active {
  color: white;
  background: var(--green);
  border-color: var(--green);
}
.slide-jump span {
  color: inherit;
  font-family: Avenir, "Trebuchet MS", sans-serif;
}
.lesson-main {
  min-width: 0;
}
.progress-track {
  height: 9px;
  overflow: hidden;
  background: #d9e0ea;
  border-radius: 999px;
  margin-bottom: 16px;
}
#progress-fill {
  display: block;
  height: 100%;
  width: 0;
  background: linear-gradient(90deg, var(--green), var(--gold));
  transition: width .25s ease;
}
.lesson-stage {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
}
.slide-frame,
.slide-copy,
.media-card,
.qa-card,
.transcript-slide {
  background: rgba(255,255,255,.96);
  border: 1px solid var(--line);
  border-radius: 16px;
  box-shadow: 0 18px 42px rgba(36, 52, 71, .1);
}
.slide-frame {
  min-height: clamp(560px, calc(100vh - 220px), 760px);
  display: grid;
  place-items: center;
  padding: clamp(18px, 3vw, 44px);
  overflow: auto;
}
.slide {
  width: min(100%, 1040px);
  min-height: 560px;
  display: grid;
  align-content: center;
  gap: 24px;
  padding: clamp(24px, 5vw, 70px);
  color: #101828;
  background:
    linear-gradient(145deg, rgba(255,255,255,.97), rgba(247,250,252,.98)),
    radial-gradient(circle at bottom right, rgba(15, 118, 110, .13), transparent 18rem);
  border: 1px solid #e5eaf0;
  border-radius: 18px;
  box-shadow: inset 0 0 0 1px rgba(255,255,255,.75);
}
.slide h1,
.slide h2 {
  margin: 0;
  font-size: clamp(34px, 5vw, 62px);
  line-height: .98;
}
.slide h3 {
  margin: 0;
  font-size: 28px;
}
.slide p,
.slide li,
.slide td,
.slide th {
  font-size: clamp(18px, 2vw, 25px);
  line-height: 1.35;
}
.slide ul,
.slide ol {
  margin: 0;
  padding-left: 1.25em;
}
.slide li + li { margin-top: .45em; }
.slide table {
  width: 100%;
  border-collapse: collapse;
  font-family: Avenir, "Trebuchet MS", sans-serif;
}
.slide th,
.slide td {
  border-bottom: 1px solid var(--line);
  padding: 10px;
  text-align: left;
  vertical-align: top;
}
.slide th {
  color: white;
  background: var(--slate);
}
.slide pre {
  white-space: pre-wrap;
  overflow: auto;
  padding: 18px;
  color: #e6edf3;
  background: #17202d;
  border-radius: 12px;
}
.slide code {
  font-family: "SFMono-Regular", Consolas, monospace;
  font-size: .82em;
}
.slide-figure {
  margin: 0;
  display: grid;
  place-items: center;
  gap: 12px;
}
.slide-figure img,
.slide img {
  max-width: 100%;
  max-height: 390px;
  object-fit: contain;
}
.slide-figure figcaption {
  color: var(--muted);
  font: 700 14px/1.2 Avenir, "Trebuchet MS", sans-serif;
}
/* In-slide diagrams: pure HTML/CSS replacements for generated raster art. */
.slide .diagram {
  width: 100%;
  font-family: Avenir, "Trebuchet MS", sans-serif;
  font-size: clamp(13px, 1.5vw, 16px);
  line-height: 1.3;
}
.slide .diagram-split {
  display: grid;
  grid-template-columns: minmax(0, .85fr) minmax(0, 1.15fr);
  gap: 24px;
  align-items: center;
}
.slide .diagram .dg-card {
  padding: .55em .8em;
  background: white;
  border: 2px solid var(--slate);
  border-radius: 10px;
}
.slide .diagram .dg-title {
  display: block;
  font-weight: 800;
}
.slide .diagram .dg-note {
  display: block;
  color: var(--muted);
  font-size: .88em;
}
.slide .diagram .dg-arrow {
  align-self: center;
  color: var(--slate);
  font-weight: 800;
  white-space: nowrap;
}
.slide .diagram .dg-caption {
  margin-top: .9em;
  color: var(--muted);
  font-weight: 700;
  font-size: .92em;
}
.slide .diagram .dg-badge {
  display: inline-block;
  margin-right: .6em;
  padding: .2em .7em;
  color: white;
  background: var(--slate);
  border-radius: 999px;
  font-weight: 800;
  font-size: .88em;
}
/* Decision guide: question rows routing to outcome cards. */
.slide .diagram-decision {
  display: grid;
  grid-template-columns: minmax(0, 1.1fr) auto minmax(0, 1fr);
  gap: .55em .7em;
  align-items: center;
}
.slide .diagram-decision .dg-question {
  padding: .5em .8em;
  background: var(--soft);
  border: 2px solid var(--blue);
  border-radius: 10px;
  font-weight: 700;
}
.slide .diagram-decision .dg-no {
  grid-column: 1;
  justify-self: center;
  color: var(--muted);
  font-weight: 700;
  font-size: .85em;
}
/* Escalation staircase with lanes. */
.slide .diagram-lanes {
  display: grid;
  grid-template-columns: 7.5em repeat(3, minmax(0, 1fr));
  gap: .5em .6em;
  align-items: center;
}
.slide .diagram-lanes .dg-lane {
  font-weight: 800;
  color: var(--slate);
  text-align: right;
  padding-right: .4em;
}
.slide .diagram-lanes .dg-arrow {
  text-align: right;
}
.slide .diagram-lanes .dg-return {
  grid-column: 2 / -1;
  padding: .45em .8em;
  background: var(--soft);
  border: 2px dashed var(--green);
  border-radius: 10px;
  font-weight: 700;
}
/* Metric shift rows: current state, arrow, target state. */
.slide .diagram-shift {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(0, 1fr) auto minmax(0, 1fr);
  gap: .5em .7em;
  align-items: center;
}
.slide .diagram-shift .dg-metric {
  font-weight: 800;
}
.slide .diagram-shift .dg-metric .dg-note {
  font-weight: 400;
}
.slide .diagram-shift .dg-current {
  padding: .4em .8em;
  text-align: center;
  background: #fdeaea;
  border: 2px solid #c0504d;
  border-radius: 999px;
  font-weight: 700;
}
.slide .diagram-shift .dg-target {
  padding: .4em .8em;
  text-align: center;
  background: #e7f4ef;
  border: 2px solid var(--green);
  border-radius: 999px;
  font-weight: 700;
}
/* Pipeline flow: stages joined by arrows, with an optional return path. */
.slide .diagram-flow {
  display: flex;
  align-items: stretch;
  gap: .45em;
}
.slide .diagram-flow .dg-card {
  flex: 1 1 0;
  min-width: 0;
}
.slide .diagram-flow + .dg-return-path,
.slide .diagram .dg-return-path {
  margin-top: .6em;
  padding: .45em .8em;
  text-align: right;
  color: #8a3b38;
  background: #fdf1f0;
  border: 2px dashed #c0504d;
  border-radius: 10px;
  font-weight: 700;
}
/* Milestone timeline: dots along a track with compact labels. */
.slide .diagram-timeline {
  position: relative;
  display: grid;
  grid-auto-flow: column;
  grid-auto-columns: minmax(0, 1fr);
  gap: .4em;
  text-align: center;
}
.slide .diagram-timeline::before {
  content: "";
  position: absolute;
  top: .4em;
  left: 4%;
  right: 4%;
  height: 4px;
  background: var(--line);
  border-radius: 999px;
}
.slide .diagram-timeline .dg-stop {
  display: grid;
  gap: .3em;
  justify-items: center;
}
.slide .diagram-timeline .dg-dot {
  position: relative;
  width: 1em;
  height: 1em;
  background: var(--green);
  border-radius: 50%;
  box-shadow: 0 0 0 3px #e7f4ef;
}
.slide .diagram-timeline .dg-stop:nth-child(even) .dg-dot {
  background: var(--blue);
  box-shadow: 0 0 0 3px var(--soft);
}
.slide-copy {
  padding: 22px;
}
#slide-counter {
  margin: 0 0 8px;
  color: var(--blue);
  font: 700 13px/1 Avenir, "Trebuchet MS", sans-serif;
  letter-spacing: .06em;
  text-transform: uppercase;
}
.slide-copy h2 {
  margin: 0 0 18px;
  font-size: 30px;
  line-height: 1.1;
}
details {
  margin-top: 13px;
  padding-top: 13px;
  border-top: 1px solid var(--line);
}
summary {
  cursor: pointer;
  font: 700 14px/1.2 Avenir, "Trebuchet MS", sans-serif;
}
.lesson-controls {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content: space-between;
  margin: 16px 0;
}
.lesson-controls button,
.lesson-controls .next-topic-button,
.qa-card button {
  border: 0;
  border-radius: 999px;
  padding: 12px 16px;
  color: white;
  background: var(--slate);
  cursor: pointer;
}
.lesson-controls .next-topic-button {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  margin-left: auto;
  background: var(--green);
  text-decoration: none;
}
.lesson-controls .next-topic-button[hidden] {
  display: none;
}
.lesson-controls button:disabled {
  cursor: not-allowed;
  opacity: .45;
}
.lesson-controls button[aria-pressed="true"] {
  background: var(--green);
}
#subtitle-box {
  position: sticky;
  bottom: 18px;
  z-index: 2;
  margin: 0 auto 14px;
  width: min(900px, 92%);
  padding: 14px 18px;
  color: white;
  background: rgba(24, 33, 47, .92);
  border-radius: 14px;
  box-shadow: 0 18px 40px rgba(24,33,47,.28);
  font: 18px/1.45 Avenir, "Trebuchet MS", sans-serif;
}
.media-card,
.qa-card {
  margin-top: 18px;
  padding: 20px;
}
.qa-card textarea {
  width: 100%;
  margin: 8px 0 10px;
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: 10px;
}
.qa-card pre {
  white-space: pre-wrap;
  font-family: Avenir, "Trebuchet MS", sans-serif;
}
.transcript-page main {
  max-width: 1120px;
  padding: 32px 0 60px;
}
.transcript-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(300px, .7fr);
  gap: 18px;
}
.transcript-slide {
  margin: 18px 0;
  padding: 20px;
}
.static-slide .slide {
  min-height: 320px;
  transform-origin: top left;
}
.site-forward main {
  padding: 48px 0;
}
@media (max-width: 980px) {
  .hero-briefs {
    grid-template-columns: 1fr;
  }
  .hero-briefs span {
    min-height: 0;
  }
  .part-band,
  .lesson-shell,
  .lesson-stage,
  .transcript-grid {
    grid-template-columns: 1fr;
  }
  .lesson-rail {
    position: static;
    max-height: none;
  }
  .slide-frame {
    min-height: 420px;
    padding: 12px;
  }
  .slide {
    min-height: 380px;
  }
}