:root {
  color-scheme: dark;
  --bg: #07111f;
  --panel: #0d1b2c;
  --panel-2: #12243a;
  --text: #f7f9fc;
  --muted: #bdc9d8;
  --accent: #67d2ff;
  --accent-2: #a4e7ff;
  --border: #57708e;
  --focus: #ffd166;
  --success: #7ee2a8;
  --danger: #ff9b9b;
}
* { box-sizing: border-box; }
html, body {
  min-height: 100%;
  margin: 0;
  background: radial-gradient(circle at 10% 0%, #163151 0, var(--bg) 42rem);
  color: var(--text);
  font-family: system-ui, -apple-system, "Segoe UI", sans-serif;
  line-height: 1.45;
}
body { padding: clamp(.6rem, 2vw, 1.5rem); }
button, input, select { font: inherit; }
button, select {
  border: 1px solid var(--border);
  border-radius: .55rem;
  background: var(--panel-2);
  color: var(--text);
  padding: .6rem .8rem;
}
button { cursor: pointer; }
button:hover { border-color: var(--accent); }
button:focus-visible, input:focus-visible, select:focus-visible, .stage:focus-visible,
.region-button:focus-visible, .skip-link:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 3px;
}
.skip-link {
  position: fixed;
  z-index: 100;
  left: 1rem;
  top: -5rem;
  background: var(--focus);
  color: #111;
  padding: .65rem 1rem;
  border-radius: .4rem;
  font-weight: 800;
}
.skip-link:focus { top: 1rem; }
.lesson-shell { width: min(1620px, 100%); margin: 0 auto; }
.lesson-header {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 1rem;
  margin: 0 0 .8rem;
}
.lesson-header h1 { margin: .1rem 0; font-size: clamp(1.2rem, 2.3vw, 2rem); }
.slide-title, #status, .focus-description, #focusPosition { color: var(--muted); }
.slide-title { margin: .2rem 0 0; }
#status { margin: 0; text-align: right; }
.eyebrow {
  color: var(--accent-2);
  font-size: .75rem;
  font-weight: 800;
  letter-spacing: .12em;
  margin: 0;
  text-transform: uppercase;
}
.lesson-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(19rem, 25rem);
  gap: 1rem;
  align-items: start;
}
.stage-column, .focus-panel, .transcript-panel {
  border: 1px solid var(--border);
  border-radius: .9rem;
  background: var(--panel);
  box-shadow: 0 1.2rem 3rem rgba(0,0,0,.28);
  overflow: hidden;
}
.stage {
  position: relative;
  display: grid;
  place-items: center;
  width: 100%;
  aspect-ratio: 16 / 9;
  overflow: hidden;
  background: #02060b;
}
.source-fallback {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: contain;
}
#lessonCanvas { position: relative; z-index: 1; display: block; width: 100%; height: 100%; }
.loading {
  position: absolute;
  z-index: 5;
  inset: 0;
  display: grid;
  place-items: center;
  background: #06101d;
  color: var(--muted);
}
.loading[hidden] { display: none; }
.captions {
  position: absolute;
  z-index: 4;
  left: 5%;
  right: 5%;
  bottom: clamp(.6rem, 3vw, 2rem);
  width: fit-content;
  max-width: 90%;
  margin: auto;
  padding: .4em .7em;
  border: 2px solid rgba(255,255,255,.25);
  border-radius: .35em;
  background: rgba(0,0,0,.92);
  color: #fff;
  font-size: clamp(1rem, 2.4vw, 1.8rem);
  font-weight: 700;
  text-align: center;
}
.captions[data-position="top"] { top: clamp(.6rem, 3vw, 2rem); bottom: auto; }
.region-layer { position: absolute; z-index: 3; inset: 0; pointer-events: none; }
.region-button {
  position: absolute;
  pointer-events: auto;
  border: 2px dashed transparent;
  background: transparent;
  color: transparent;
  min-width: 2rem;
  min-height: 2rem;
}
.region-button:hover, .region-button:focus-visible {
  border-color: var(--focus);
  background: rgba(255,209,102,.12);
}
.transport, .focus-panel, .transcript-panel { padding: 1rem; }
.transport-row { display: flex; align-items: center; gap: .6rem; flex-wrap: wrap; }
.transport-row + .transport-row { margin-top: .7rem; }
.seek-label { flex: 1 1 12rem; }
#seek { width: 100%; accent-color: var(--accent); }
#timeOutput { min-width: 7.5rem; color: var(--muted); font-variant-numeric: tabular-nums; }
.secondary-controls label { display: flex; align-items: center; gap: .4rem; color: var(--muted); }
#volume { width: 6rem; accent-color: var(--accent); }
.focus-heading, .panel-heading {
  display: flex;
  align-items: start;
  justify-content: space-between;
  gap: .7rem;
}
.focus-heading h2 { margin: .2rem 0 .35rem; font-size: 1.1rem; }
.focus-description { margin: 0 0 .8rem; }
.focus-actions { display: grid; grid-template-columns: repeat(3, 1fr); gap: .4rem; }
.focus-list, .transcript-list {
  max-height: min(60vh, 42rem);
  overflow: auto;
  margin: .9rem 0 0;
  padding: 0;
  list-style: none;
}
.focus-list li + li, .transcript-list li + li { margin-top: .4rem; }
.focus-list button, .transcript-list button {
  width: 100%;
  display: grid;
  grid-template-columns: auto 1fr;
  gap: .55rem;
  text-align: left;
  color: var(--muted);
}
.focus-state { min-width: 1.8rem; color: var(--accent-2); font-weight: 800; }
.focus-list button[aria-current="true"], .transcript-list button[aria-current="true"] {
  border-color: var(--accent);
  background: #15344f;
  color: var(--text);
}
.focus-list button[data-completed="true"] .focus-state { color: var(--success); }
.transcript-panel { grid-column: 1 / -1; }
.transcript-label { display: block; color: var(--accent-2); font-weight: 800; }
.error-status {
  padding: .7rem;
  border: 2px solid var(--danger);
  border-radius: .5rem;
  background: #2c1118;
  color: var(--danger);
}
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}
@media (max-width: 920px) {
  .lesson-grid { grid-template-columns: 1fr; }
  .focus-list { max-height: 16rem; }
  .transcript-panel { grid-column: 1; }
}
@media (max-width: 600px) {
  body { padding: .35rem; }
  .lesson-header { align-items: start; }
  .primary-controls button { flex: 1 1 auto; }
  .seek-label { order: 5; flex-basis: 100%; }
  .focus-actions { grid-template-columns: 1fr; }
  .secondary-controls label { width: 100%; justify-content: space-between; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition: none !important; }
}
@media (forced-colors: active) {
  button, select, .stage-column, .focus-panel, .transcript-panel {
    border: 1px solid ButtonText;
  }
  .captions { forced-color-adjust: none; }
}
:fullscreen .lesson-shell, .lesson-shell:fullscreen {
  width: 100%;
  height: 100%;
  padding: .5rem;
  background: var(--bg);
}
:fullscreen .lesson-header, .lesson-shell:fullscreen .lesson-header { display: none; }
:fullscreen .lesson-grid, .lesson-shell:fullscreen .lesson-grid {
  height: 100%;
  grid-template-columns: minmax(0,1fr) minmax(16rem,22rem);
}
:fullscreen .stage-column, .lesson-shell:fullscreen .stage-column {
  display: flex;
  flex-direction: column;
}
:fullscreen .stage, .lesson-shell:fullscreen .stage { flex: 1; aspect-ratio: auto; }