/* K4 Live Demo — scoped under #demo (matches landing Literata/Sora midnight lacquer) */
#demo {
  --gold: #c4a574;
  --ink-soft: #2c322c;
  --walnut-mid: #4a3428;
  background:
    radial-gradient(ellipse 50% 40% at 80% 0%, rgba(45, 86, 72, 0.4), transparent 60%),
    radial-gradient(ellipse 40% 35% at 10% 90%, rgba(74, 52, 40, 0.35), transparent 55%),
    linear-gradient(165deg, #151310 0%, #0a0c0b 45%, #080908 100%);
  color: var(--ivory);
}
#demo::before {
  content: "";
  position: absolute;
  inset: 0;
  opacity: 0.18;
  pointer-events: none;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='3' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)' opacity='0.55'/%3E%3C/svg%3E");
  mix-blend-mode: soft-light;
}
#demo .wrap-demo {
  width: min(920px, calc(100% - 2 * var(--pad)));
  margin: 0 auto;
  position: relative;
  z-index: 1;
}
#demo h2 {
  color: var(--ivory);
  max-width: 16ch;
}
#demo .support {
  color: rgba(243, 241, 234, 0.62);
}
#demo .demo-badge {
  display: inline-block;
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--gold);
  margin-bottom: 0.75rem;
}
#demo button, #demo input { font: inherit; }

#demo .panel {
  background: rgba(243, 241, 234, 0.04);
  border: 1px solid var(--line-light);
  border-radius: 2px;
  padding: clamp(1.15rem, 3vw, 1.65rem);
  backdrop-filter: blur(8px);
}
#demo .field-label {
  display: block;
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: rgba(243, 241, 234, 0.55);
  margin-bottom: 0.55rem;
}
#demo .url-row {
  display: flex;
  gap: 0.65rem;
  flex-wrap: wrap;
}
#demo .url-row input {
  flex: 1 1 220px;
  min-width: 0;
  background: rgba(0, 0, 0, 0.35);
  border: 1px solid rgba(243, 241, 234, 0.18);
  color: var(--ivory);
  padding: 0.85rem 1rem;
  border-radius: 2px;
  outline: none;
  transition: border-color 0.2s;
}
#demo .url-row input:focus {
  border-color: rgba(196, 165, 116, 0.65);
}
#demo .url-row input::placeholder {
  color: rgba(243, 241, 234, 0.35);
}

#demo .btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  border: 1px solid transparent;
  cursor: pointer;
  padding: 0.85rem 1.25rem;
  border-radius: 2px;
  transition: transform 0.2s var(--ease), background 0.2s, opacity 0.2s, border-color 0.2s;
  white-space: nowrap;
  font-family: var(--font-body);
  font-weight: 600;
  font-size: 0.92rem;
  text-decoration: none;
}
#demo .btn:active { transform: scale(0.98); }
#demo .btn:disabled { opacity: 0.45; cursor: not-allowed; }
#demo .btn-solid {
  background: var(--moss-bright) !important;
  color: var(--ivory) !important;
  border-color: transparent;
}
#demo .btn-solid:hover:not(:disabled) { background: #356554 !important; }
#demo .btn-ghost {
  background: transparent !important;
  color: var(--ivory) !important;
  border: 1px solid rgba(243, 241, 234, 0.28);
}
#demo .btn-ghost:hover:not(:disabled) {
  border-color: rgba(243, 241, 234, 0.55);
  background: rgba(243, 241, 234, 0.05) !important;
}
#demo .btn-sm {
  padding: 0.55rem 0.9rem;
  font-size: 0.9rem;
}

#demo .hint {
  margin-top: 0.85rem;
  font-size: 0.88rem;
  color: rgba(243, 241, 234, 0.5);
}

#demo .samples {
  margin-top: 1.35rem;
  padding-top: 1.2rem;
  border-top: 1px solid var(--line-light);
}
#demo .samples h3 {
  font-size: 0.95rem;
  font-family: var(--font-body);
  font-weight: 500;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: rgba(243, 241, 234, 0.55);
  margin: 0 0 0.75rem;
}
#demo .sample-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 0.65rem;
}
#demo .sample-card {
  text-align: left;
  background: rgba(0, 0, 0, 0.28);
  border: 1px solid rgba(243, 241, 234, 0.12);
  color: var(--ivory);
  padding: 0.95rem 1rem;
  border-radius: 2px;
  cursor: pointer;
  transition: border-color 0.2s, background 0.2s;
  font-family: var(--font-body);
}
#demo .sample-card:hover {
  border-color: rgba(196, 165, 116, 0.55);
  background: rgba(45, 86, 72, 0.22);
}
#demo .sample-card strong {
  display: block;
  font-family: var(--font-display);
  font-size: 1.05rem;
  font-weight: 500;
  margin-bottom: 0.25rem;
}
#demo .sample-card small {
  color: rgba(243, 241, 234, 0.5);
  font-size: 0.82rem;
}

#demo .progress {
  display: none;
  margin-top: 1.25rem;
}
#demo .progress.visible { display: block; }
#demo .progress-track {
  height: 2px;
  background: rgba(243, 241, 234, 0.12);
  overflow: hidden;
  margin-bottom: 0.75rem;
}
#demo .progress-bar {
  height: 100%;
  width: 30%;
  background: linear-gradient(90deg, var(--moss-bright), var(--gold));
  animation: demo-slide 1.4s ease-in-out infinite;
}
#demo .progress-steps {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1rem;
  font-size: 0.85rem;
  color: rgba(243, 241, 234, 0.55);
}
#demo .progress-steps .on { color: var(--gold); }
#demo .progress-steps .done { color: rgba(243, 241, 234, 0.85); }

#demo .error-box {
  display: none;
  margin-top: 1rem;
  padding: 0.9rem 1rem;
  border-left: 3px solid #a65d4a;
  background: rgba(166, 93, 74, 0.12);
  color: #f0d4cc;
  font-size: 0.92rem;
}
#demo .error-box.visible { display: block; }

#demo .lesson {
  display: none;
  margin-top: 1.75rem;
}
#demo .lesson.visible { display: block; }

#demo .lesson-head {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 1.25rem;
}
#demo .lesson-head h3 {
  font-family: var(--font-display);
  font-size: clamp(1.4rem, 3.5vw, 1.85rem);
  font-weight: 500;
  max-width: 22ch;
  margin: 0 0 0.45rem;
  color: var(--ivory);
}
#demo .meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.45rem;
}
#demo .chip {
  font-size: 0.75rem;
  letter-spacing: 0.04em;
  padding: 0.28rem 0.55rem;
  border: 1px solid rgba(243, 241, 234, 0.2);
  color: rgba(243, 241, 234, 0.75);
  border-radius: 2px;
}
#demo .chip.gold {
  border-color: rgba(196, 165, 116, 0.45);
  color: var(--gold);
}

#demo .audio-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
  align-items: center;
  margin-bottom: 1.35rem;
}
#demo audio {
  width: min(100%, 360px);
  height: 36px;
  filter: invert(0.9) hue-rotate(180deg);
}

#demo .teacher-card {
  background: linear-gradient(135deg, rgba(45, 86, 72, 0.35), rgba(46, 33, 26, 0.4));
  border: 1px solid rgba(196, 165, 116, 0.22);
  padding: 1.15rem 1.25rem;
  margin-bottom: 1.25rem;
  border-radius: 2px;
}
#demo .teacher-card .kicker {
  font-size: 0.7rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--gold);
  margin-bottom: 0.45rem;
}
#demo .teacher-card #teacher-text {
  font-family: var(--font-display);
  font-size: clamp(1.05rem, 2.4vw, 1.25rem);
  line-height: 1.45;
  margin: 0 0 0.9rem;
  color: var(--ivory);
}
#demo .teacher-actions { display: flex; flex-wrap: wrap; gap: 0.5rem; }

#demo .steps-nav {
  display: flex;
  gap: 0.4rem;
  flex-wrap: wrap;
  margin-bottom: 1rem;
}
#demo .step-pill {
  background: transparent;
  border: 1px solid rgba(243, 241, 234, 0.18);
  color: rgba(243, 241, 234, 0.6);
  padding: 0.4rem 0.7rem;
  border-radius: 2px;
  cursor: pointer;
  font-size: 0.8rem;
  transition: all 0.2s;
  font-family: var(--font-body);
}
#demo .step-pill.active {
  background: rgba(243, 241, 234, 0.1);
  border-color: rgba(196, 165, 116, 0.55);
  color: var(--ivory);
}

#demo .practice-box {
  border: 1px solid var(--line-light);
  padding: 1rem 1.1rem;
  margin-bottom: 1.15rem;
  background: rgba(0, 0, 0, 0.22);
}
#demo .practice-box h4 {
  font-size: 0.78rem;
  font-family: var(--font-body);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: rgba(243, 241, 234, 0.5);
  margin: 0 0 0.4rem;
  font-weight: 500;
}
#demo #practice-text {
  color: rgba(243, 241, 234, 0.85);
  margin: 0;
}

#demo .notes-row, #demo .chords-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-top: 0.75rem;
}
#demo .note {
  min-width: 2.6rem;
  text-align: center;
  padding: 0.45rem 0.55rem;
  background: var(--ivory);
  color: var(--ink);
  font-weight: 600;
  font-size: 0.92rem;
  border-radius: 2px;
}
#demo .chord {
  padding: 0.45rem 0.7rem;
  border: 1px solid rgba(196, 165, 116, 0.5);
  color: var(--gold);
  font-weight: 500;
  border-radius: 2px;
}

#demo .bars { margin-top: 0.5rem; }
#demo .bars h4 {
  font-family: var(--font-display);
  font-size: 0.95rem;
  font-weight: 500;
  margin: 0 0 0.65rem;
  color: var(--ivory);
}
#demo .bar-grid { display: grid; gap: 0.5rem; }
#demo .bar {
  display: grid;
  grid-template-columns: 3.5rem 1fr auto;
  gap: 0.65rem;
  align-items: center;
  padding: 0.65rem 0.75rem;
  background: rgba(243, 241, 234, 0.03);
  border: 1px solid rgba(243, 241, 234, 0.08);
  font-size: 0.9rem;
}
#demo .bar .bn {
  color: var(--gold);
  font-variant-numeric: tabular-nums;
  font-size: 0.8rem;
}
#demo .bar .melody { color: rgba(243, 241, 234, 0.8); }
#demo .bar .ch { color: rgba(243, 241, 234, 0.45); font-size: 0.82rem; }

#demo .step-nav-btns {
  display: flex;
  gap: 0.55rem;
  margin-top: 1.1rem;
}

#demo .demo-legal {
  margin-top: 2rem;
  padding-top: 1.25rem;
  border-top: 1px solid var(--line-light);
  font-size: 0.78rem;
  color: rgba(243, 241, 234, 0.4);
  line-height: 1.5;
}
#demo .demo-legal code {
  font-size: 0.85em;
  color: rgba(243, 241, 234, 0.55);
}

@keyframes demo-slide {
  0% { transform: translateX(-100%); }
  50% { transform: translateX(200%); }
  100% { transform: translateX(-100%); }
}

@media (max-width: 560px) {
  #demo .bar { grid-template-columns: 1fr; gap: 0.25rem; }
}

@media (prefers-reduced-motion: reduce) {
  #demo .progress-bar { animation: none; width: 60%; }
}