html:has(.lesson-page),
html:has(.lesson-page) body {
  height: 100%;
  height: 100dvh;
  max-height: 100dvh;
  overflow: hidden;
  scrollbar-width: none;
}
html:has(.lesson-page)::-webkit-scrollbar,
html:has(.lesson-page) body::-webkit-scrollbar {
  display: none;
}

.app-screen.lesson-page {
  display: flex;
  flex-direction: column;
  height: 100%;
  height: 100dvh;
  max-height: 100dvh;
  overflow: hidden;
  padding-bottom: 20px;
  color: #06344f;
  cursor: default;
  caret-color: transparent;
  user-select: none;
  -webkit-user-select: none;
  -webkit-touch-callout: none;
}
.app-screen.lesson-page *,
.app-screen.lesson-page *::before,
.app-screen.lesson-page *::after {
  caret-color: transparent;
  user-select: none;
  -webkit-user-select: none;
}
.app-screen.lesson-page a,
.app-screen.lesson-page button {
  cursor: pointer;
}
.app-screen.lesson-page img,
.app-screen.lesson-page svg {
  -webkit-user-drag: none;
}

#page-root[data-page="lesson"] {
  display: flex;
  flex: 1 1 auto;
  min-height: 0;
}

.lesson-page {
  background: transparent;
}

.lesson-bg {
  position: absolute;
  inset: 0;
  z-index: 0;
  pointer-events: none;
}
.lesson-bg-img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center 28%;
}

.lesson-hud,
.lesson-main {
  position: relative;
  z-index: 1;
}

.lesson-hud {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  align-items: center;
  flex: 0 0 auto;
  gap: 12px;
  padding: clamp(16px, 3.6vh, 36px) calc(clamp(18px, 6.4vw, 110px) + 24px) 4px;
}

@media (max-width: 980px) {
  .lesson-hud {
    grid-template-columns: auto minmax(0, 1fr) auto;
  }
}

.lesson-hud-left {
  display: flex;
  align-items: center;
  gap: 14px;
  min-width: 0;
  position: relative;
  z-index: 4;
}

.lesson-hud .brand-logo {
  height: clamp(40px, 6.5vh, 52px);
  margin: 0;
}

.lesson-quit,
.lesson-speaker,
.lesson-settings {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  border-radius: 999px;
  background: #fff;
  box-shadow: 0 6px 16px rgb(16 84 115 / 0.16);
  color: #1d4c6b;
  font-weight: 800;
}

.lesson-quit {
  position: relative;
  z-index: 5;
  gap: 8px;
  padding: 8px 18px 8px 14px;
  font-size: 16px;
}

.lesson-quit-icon {
  display: block;
  flex: none;
}

.lesson-hud-center {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  min-width: 0;
  max-width: 100%;
  position: relative;
  z-index: 1;
}

.lesson-hud-title {
  margin: 0;
  font-family: 'Fredoka', 'Baloo 2', sans-serif;
  font-size: clamp(20px, 3.4vh, 32px);
  font-weight: 800;
  letter-spacing: -0.04em;
  line-height: 1;
  color: #002f55;
  text-align: center;
}

.lesson-steps {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 10px;
  margin: 0;
  padding: 0;
  list-style: none;
  box-sizing: border-box;
  width: 100%;
  max-width: 100%;
}
.lesson-steps[data-count="12"],
.lesson-steps[data-count="24"] {
  gap: 6px;
}
.lesson-steps[data-count="12"] .lesson-step,
.lesson-steps[data-count="24"] .lesson-step {
  width: 26px;
  height: 26px;
  font-size: 13px;
}
.lesson-steps[data-count="24"] {
  gap: 4px;
}
.lesson-steps[data-count="24"] .lesson-step {
  width: 22px;
  height: 22px;
  font-size: 11px;
}

.lesson-step {
  display: grid;
  place-items: center;
  width: 34px;
  height: 34px;
  border-radius: 50%;
  background: #fff;
  color: #7b8fa3;
  font-family: 'Nunito', sans-serif;
  font-size: 16px;
  font-weight: 800;
  box-shadow: 0 2px 0 rgb(16 84 115 / 0.12);
}

.lesson-step.is-current {
  background: #ffd35c;
  color: #6b4a00;
  box-shadow: 0 2px 0 #e0b63d;
}
.lesson-step.is-done {
  background: #3ecf62;
  color: #fff;
  box-shadow: 0 2px 0 #2ea24d;
}
.lesson-step.is-retry {
  background: #ffd35c;
  color: #6b4a00;
  box-shadow: 0 2px 0 #e0b63d;
}

.lesson-tools {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  position: relative;
  z-index: 4;
  gap: 10px;
}

.lesson-speaker,
.lesson-settings {
  width: 44px;
  height: 44px;
  padding: 0;
  border: 0;
  color: #2a6284;
}

.lesson-settings img {
  display: block;
  width: 22px;
  height: 22px;
}

.lesson-main {
  display: flex;
  justify-content: center;
  align-items: stretch;
  flex: 1 1 auto;
  min-height: 0;
  width: 100%;
  padding: 8px 24px 24px;
}

.lesson-card[hidden] { display: none !important; }

.lesson-card {
  position: relative;
  display: flex;
  flex-direction: column;
  width: min(980px, 100%);
  height: 100%;
  min-height: 0;
  max-height: 100%;
  padding: clamp(10px, 1.6vh, 18px);
  overflow: hidden;
  border: 6px solid #fff;
  border-radius: 48px;
  background: #efe4cf;
  box-shadow: 0 0 22px 4px rgb(18 56 32 / 0.28);
  text-align: center;
}

.lesson-card::before {
  content: '';
  position: absolute;
  inset: 12px;
  border-radius: 36px;
  border: 2px dashed rgb(120 90 50 / 0.32);
  pointer-events: none;
}

.lesson-card-inner {
  position: relative;
  z-index: 1;
  display: flex;
  flex-direction: column;
  flex: 1 1 auto;
  min-height: 0;
  padding: clamp(8px, 1.8vh, 18px) clamp(16px, 3vw, 36px) clamp(8px, 1.6vh, 22px);
  overflow: hidden;
}

.lesson-complete h2 {
  margin: 0;
  font-family: 'Baloo 2', 'Fredoka', cursive;
  font-weight: 800;
  color: #102a43;
}

.lesson-card-title {
  flex: 0 0 auto;
  margin: 0 auto;
  padding: 6px 10px;
  transform: none;
  color: #002f55;
  font-family: 'Fredoka', sans-serif;
  font-size: clamp(1.7rem, 5vh, 3.6rem);
  font-weight: 800;
  line-height: 1;
  letter-spacing: -0.04em;
  text-align: center;
}

.lesson-help {
  flex: 0 0 auto;
  margin: clamp(4px, 1vh, 8px) auto clamp(8px, 1.6vh, 18px);
  max-width: 28em;
  font-size: clamp(14px, 2.1vh, 18px);
  font-weight: 700;
  color: #35577a;
}

.staff-row {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  flex: 0 1 auto;
  min-width: 0;
  min-height: 0;
  width: 100%;
}
.staff-nudge {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 12px;
  flex: 0 0 var(--staff-nudge-col, 112px);
  width: var(--staff-nudge-col, 112px);
}
.staff-nudge[hidden] { display: none; }
.staff-row:has(.staff-nudge:not([hidden])) {
  --staff-nudge-col: 112px;
}
.staff-row:has(.staff-nudge:not([hidden])) .staff-panel {
  margin-left: calc(var(--staff-nudge-col) + 12px);
}
.nudge-btn {
  display: grid;
  place-items: center;
  width: 76px;
  height: 76px;
  padding: 0;
  border: 3px solid #2b4a6f;
  border-radius: 20px;
  background: #fbf6ef;
  color: #2b4a6f;
  box-shadow: inset 0 -6px 0 rgb(43 74 111 / 0.08);
  cursor: pointer;
}
.nudge-btn svg {
  display: block;
  width: 42px;
  height: 42px;
}
.nudge-btn:hover:not(:disabled) { background: #fff6e8; }
.nudge-btn:disabled { opacity: 0.38; cursor: default; }
.nudge-btn.is-check {
  display: inline-flex;
  flex-direction: row;
  align-items: center;
  justify-content: center;
  gap: 6px;
  width: auto;
  min-width: 76px;
  height: 52px;
  padding: 0 16px;
  margin-top: 4px;
  border-radius: 999px;
  background: #3ecf62;
  border-color: #2ea24d;
  color: #fff;
  font-family: 'Nunito', sans-serif;
  font-size: 18px;
  font-weight: 800;
  box-shadow: inset 0 -6px 0 rgb(25 110 50 / 0.18);
}
.nudge-btn.is-check svg {
  width: 22px;
  height: 22px;
}
.nudge-btn.is-check:hover:not(:disabled) { background: #47d86b; }

.staff-panel {
  position: relative;
  display: flex;
  flex: 1 1 auto;
  box-sizing: border-box;
  min-width: 0;
  min-height: 0;
  margin: 0;
  width: auto;
  max-width: 100%;
  max-height: 100%;
  aspect-ratio: var(--staff-aspect, 24 / 7.1);
  padding: 8px 10px;
  overflow: hidden;
  border: 3px solid #c9b496;
  border-radius: 22px;
  background: #fff;
  box-shadow: 0 2px 0 rgb(120 90 50 / 0.08);
}
.staff-panel.is-hearing {
  animation: staff-hear-glow 0.7s ease;
}

.staff-host {
  display: block;
  flex: 1 1 auto;
  min-width: 0;
  min-height: 0;
  width: 100%;
  height: 100%;
}

.pogo-staff {
  display: block;
  width: 100%;
  height: 100%;
  min-width: 0;
  min-height: 0;
  overflow: hidden;
}
.pogo-staff line {
  stroke: #151515;
}
.pogo-staff .staff-clef { fill: #151515; }
.pogo-staff .staff-clef.treble {
  font-family: 'Noto Sans Symbols 2', 'Segoe UI Symbol', 'Times New Roman', serif;
}
.pogo-staff .staff-brace { fill: #151515; }
.staff-note-body {
  transform-origin: 0px 0px;
}
.staff-note-letter {
  fill: #fff;
  font-family: 'Fredoka', 'Nunito', sans-serif;
  font-weight: 800;
  letter-spacing: -0.04em;
  pointer-events: none;
}
.staff-note[data-duration="half"] .staff-note-letter,
.staff-note[data-duration="whole"] .staff-note-letter {
  fill: #151515;
}
.staff-note.is-correct .staff-note-body,
.staff-note.is-done .staff-note-body {
  animation: note-pop 0.45s ease;
}
.staff-note-glyph { filter: url(#note-tint-grey); }
.staff-note.is-current .staff-note-glyph { filter: none; }
.staff-note.is-correct .staff-note-glyph,
.staff-note.is-done .staff-note-glyph { filter: url(#note-tint-green); }
.staff-note-layer.has-many .staff-note.is-current .staff-note-glyph { filter: url(#note-tint-gold); }
.staff-note-layer.has-many .staff-note.is-correct .staff-note-glyph,
.staff-note-layer.has-many .staff-note.is-done .staff-note-glyph { filter: url(#note-tint-green); }
.staff-hear-sparks {
  fill: #ffbd24;
  opacity: 0;
  transform-box: fill-box;
  transform-origin: center;
}
.staff-success-spark {
  opacity: 0;
  pointer-events: none;
  transform-box: fill-box;
  transform-origin: center;
}
.staff-note.is-correct .staff-success-spark,
.staff-note.is-hearing .staff-success-spark {
  animation: note-success-sparks 0.7s ease;
}
.staff-note.is-hearing .staff-note-body {
  animation: note-hear 0.7s ease;
}
.staff-note.is-hearing .staff-note-glyph { filter: url(#note-tint-gold); }
.staff-note.is-nudge .staff-note-body {
  animation: note-pop 0.28s ease;
}
.staff-note.is-wrong .staff-note-body {
  animation: note-nudge 0.3s ease-in-out;
}

@keyframes note-pop {
  0% { transform: scale(1); }
  40% { transform: scale(1.12); }
  100% { transform: scale(1); }
}
@keyframes note-hear {
  0% { transform: scale(1); }
  30% { transform: scale(1.2); }
  100% { transform: scale(1); }
}
@keyframes hear-sparks {
  0% { opacity: 0; transform: scale(0.6); }
  35% { opacity: 1; transform: scale(1.15); }
  100% { opacity: 0; transform: scale(1); }
}
@keyframes note-success-sparks {
  0% { opacity: 0; transform: scale(0.55); }
  35% { opacity: 1; transform: scale(1.18); }
  100% { opacity: 0; transform: scale(1); }
}

.piano-host {
  position: relative;
  display: flex;
  justify-content: center;
  flex: 0 0 auto;
  margin-top: clamp(8px, 1.8vh, 18px);
}
.piano-hand {
  position: absolute;
  z-index: 6;
  display: block;
  overflow: visible;
  pointer-events: none;
  user-select: none;
}
.piano-host.has-hand {
  overflow: visible;
}
.lesson-card:has(.piano-host.has-hand),
.lesson-card-inner:has(.piano-host.has-hand) {
  overflow: visible;
}
.app-screen.lesson-page:has(.piano-host.has-hand),
.lesson-main:has(.piano-host.has-hand) {
  overflow: visible;
}
.piano-hand[hidden] {
  display: none;
}

.lesson-listen-row {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  flex: 0 0 auto;
  gap: 14px;
  margin-top: clamp(8px, 2vh, 22px);
}

.hear-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  box-sizing: border-box;
  min-width: 168px;
  padding: 10px 22px;
  border: 0;
  border-radius: 999px;
  background: #3aa7e0;
  color: #fff;
  font-family: 'Nunito', sans-serif;
  font-size: 18px;
  font-weight: 800;
  line-height: 1;
  box-shadow: 0 4px 0 #2b86b6;
}
.hear-btn [data-hear-label] {
  display: inline-block;
  line-height: 1;
  text-align: center;
}
.hear-btn.is-playing,
.lesson-speaker.is-playing {
  animation: hear-press 0.5s ease;
}
.hear-btn.is-playing .hear-icon,
.lesson-speaker.is-playing svg {
  animation: hear-waves 0.6s ease;
}

.hear-icon {
  display: inline-flex;
}

.hear-hint {
  margin: 0;
  font-size: 15px;
  font-weight: 700;
  color: #5a7a90;
}

.pogo-piano {
  display: flex;
  justify-content: center;
  gap: 28px;
  width: min(500px, 100%);
}
.pogo-piano.is-both { width: min(980px, 100%); }

.piano-board {
  position: relative;
  display: flex;
  width: min(500px, 100%);
  height: clamp(104px, 19vh, 154px);
  overflow: hidden;
  border-radius: 12px 12px 10px 10px;
  user-select: none;
}

.piano-key {
  flex: 1;
  display: flex;
  align-items: flex-end;
  justify-content: center;
  margin-left: -3px;
  padding-bottom: 12px;
  border: 3px solid #2b4a6f;
  border-radius: 0 0 10px 10px;
  background: #fbf6ef;
  font-family: 'Nunito', sans-serif;
  font-size: 22px;
  font-weight: 800;
  color: #2b4a6f;
  box-shadow: inset 0 -8px 0 rgb(43 74 111 / 0.08);
}
.piano-key:first-child { margin-left: 0; border-radius: 12px 0 10px 10px; }
.piano-key:nth-child(7) { border-radius: 0 14px 10px 10px; }
.piano-key.is-hint {
  background: #f7c862;
  color: #5c3a10;
  z-index: 2;
}
.piano-key.is-hearing {
  animation: key-hear 0.55s ease;
}
.piano-key.is-down { transform: translateY(2px); }
.piano-key.is-wrong {
  background: #f3ddd5;
  animation: key-nudge 0.3s ease-in-out;
}

.piano-black {
  position: absolute;
  top: 0;
  z-index: 5;
  width: 9%;
  height: 62%;
  padding: 0;
  transform: translateX(-50%);
  border: 3px solid #2b4a6f;
  border-top: none;
  border-radius: 0 0 8px 8px;
  background: #33383f;
  cursor: default;
  appearance: none;
}

@keyframes key-nudge {
  0%, 100% { transform: translateX(0); }
  30% { transform: translateX(-5px); }
  60% { transform: translateX(5px); }
}
@keyframes note-nudge {
  0%, 100% { transform: translateX(0); }
  30% { transform: translateX(-6px); }
  60% { transform: translateX(6px); }
}
@keyframes key-hear {
  0% { transform: translateY(0) scale(1); filter: brightness(1); }
  35% { transform: translateY(3px) scale(0.98); filter: brightness(1.12); }
  100% { transform: translateY(0) scale(1); filter: brightness(1); }
}
@keyframes hear-press {
  0% { transform: scale(1); }
  30% { transform: scale(0.94); }
  60% { transform: scale(1.05); }
  100% { transform: scale(1); }
}
@keyframes hear-waves {
  0% { transform: scale(1); }
  40% { transform: scale(1.18) rotate(-8deg); }
  100% { transform: scale(1); }
}
@keyframes staff-hear-glow {
  0% { box-shadow: 0 2px 0 rgb(120 90 50 / 0.08); }
  35% { box-shadow: 0 0 0 5px rgb(255 189 36 / 0.55), 0 2px 0 rgb(120 90 50 / 0.08); }
  100% { box-shadow: 0 2px 0 rgb(120 90 50 / 0.08); }
}

.lesson-complete {
  align-self: center;
  width: min(720px, 100%);
  height: auto;
  justify-content: center;
  overflow: hidden;
  padding: 20px 52px 24px;
  cursor: pointer;
}

.complete-badge {
  width: min(240px, 70%);
  margin: 0 auto;
}
.complete-badge img {
  display: block;
  width: 100%;
  height: auto;
}

.complete-kicker {
  margin: 2px 0 0;
  font-size: 22px;
  font-weight: 800;
  color: #5a7a90;
}

.lesson-complete h2 {
  margin-top: 4px;
  font-size: clamp(44px, 6vw, 68px);
  line-height: 1.02;
}

.complete-message {
  margin: 6px 0 0;
  font-size: 26px;
  font-weight: 800;
  color: #35577a;
}

.complete-stars {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 14px;
  margin: 10px 0 8px;
}
.complete-star {
  display: block;
  width: 118px;
  height: 118px;
  object-fit: contain;
}

.complete-coins {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin: 0 auto;
  padding: 8px 18px;
  border-radius: 999px;
  background: #fff4cc;
  font-size: 24px;
  font-weight: 800;
  color: #a9720c;
}
.complete-coins img { display: block; }

.complete-replay {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  margin: 16px auto 0;
  padding: 10px 22px;
  border: 0;
  border-radius: 999px;
  background: #fff;
  color: #1d4c6b;
  font-family: 'Nunito', sans-serif;
  font-size: 18px;
  font-weight: 800;
  line-height: 1;
  box-shadow: 0 4px 0 rgb(16 84 115 / 0.18);
  cursor: pointer;
}
.complete-replay svg { display: block; }
.complete-replay:hover { background: #f6fbff; }

.complete-continue-hint {
  margin: 14px 0 0;
  font-size: 16px;
  font-weight: 800;
  color: #5a7a90;
}

.lesson-complete:focus {
  outline: none;
}

@media (max-width: 700px) {
  .lesson-hud {
    grid-template-columns: 1fr auto;
    padding: max(12px, env(safe-area-inset-top)) 24px 4px;
  }
  .lesson-hud-center { grid-column: 1 / -1; order: 3; }
  .lesson-card { padding: 10px; border-radius: 32px; }
  .lesson-card::before { inset: 8px; border-radius: 24px; }
  .lesson-card-inner { padding: 8px 10px 10px; }
  .piano-board { height: clamp(92px, 20vh, 124px); }
  .piano-key { font-size: 18px; }
}

.intro-modal {
  position: fixed;
  inset: 0;
  z-index: 70;
  display: grid;
  place-items: center;
  padding: 24px;
}
.intro-modal[hidden] { display: none; }
.intro-modal-backdrop {
  position: absolute;
  inset: 0;
  background: rgb(8 36 58 / 0.28);
}
.intro-modal-card {
  position: relative;
  z-index: 1;
  width: min(560px, 100%);
  padding: 36px 32px 32px;
  border-radius: 40px;
  background: linear-gradient(180deg, #f7fdff 0%, #eef8ff 100%);
  box-shadow: 0 18px 40px rgb(16 84 115 / 0.22);
  text-align: center;
  color: #16395a;
  transform-origin: calc(100% - 44px) calc(100% + 40px);
  transition: transform 420ms cubic-bezier(0.5, -0.2, 0.7, 0.3), opacity 420ms ease;
}
.intro-modal.is-minimizing .intro-modal-backdrop {
  transition: opacity 420ms ease;
  opacity: 0;
}
.intro-modal.is-minimizing .intro-modal-card {
  transform: scale(0.06);
  opacity: 0;
}
.intro-modal-card h2 {
  margin: 0 0 8px;
  font-family: 'Fredoka', 'Nunito', sans-serif;
  font-size: 28px;
  font-weight: 800;
  color: #16395a;
}
.intro-modal-card p {
  margin: 0 0 20px;
  font-size: 15px;
  font-weight: 700;
  color: #5d7d96;
}

.intro-demo {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 22px;
  margin: 0 auto 26px;
}
.intro-demo::before {
  content: '';
  grid-column: 1;
}
.intro-staff-col {
  grid-column: 2;
  min-width: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
}
.intro-note-label {
  font-family: 'Fredoka', 'Nunito', sans-serif;
  font-size: 52px;
  font-weight: 800;
  line-height: 1;
  color: #2b4a6f;
  text-align: center;
}
.intro-staff-panel {
  width: 100%;
  max-width: 190px;
  height: 220px;
}
.intro-staff-panel .staff-clef { display: none; }
.intro-staff-panel .staff-note-body {
  -webkit-transform-box: fill-box;
  transform-box: fill-box;
  transform-origin: center;
  transform: scale(1.6);
}

.intro-nudge {
  grid-column: 3;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
}
.intro-nudge-btn {
  display: grid;
  place-items: center;
  width: 52px;
  height: 52px;
  border: 3px solid #2b4a6f;
  border-radius: 16px;
  background: #fbf6ef;
  color: #2b4a6f;
  transition: background 160ms ease, transform 160ms ease;
}
.intro-nudge-btn svg { display: block; width: 28px; height: 28px; }
.intro-nudge-btn.is-check {
  width: auto;
  min-width: 52px;
  height: 38px;
  padding: 0 14px;
  border-radius: 999px;
  background: #3ecf62;
  border-color: #2ea24d;
  color: #fff;
}
.intro-nudge-btn.is-check svg { width: 18px; height: 18px; }
.intro-nudge-btn.is-active {
  background: #fff6e8;
  transform: scale(1.12);
}

.intro-modal-start {
  min-width: 160px;
  min-height: 52px;
  padding: 12px 28px;
  border: 0;
  border-radius: 999px;
  background: #2f86ff;
  color: #fff;
  font-family: 'Fredoka', 'Nunito', sans-serif;
  font-size: 18px;
  font-weight: 800;
  box-shadow: 0 4px 0 #1d6fe0;
  cursor: pointer;
  transition: background 160ms ease, opacity 160ms ease, box-shadow 160ms ease;
}
.intro-modal-start:hover:not(:disabled) { background: #247af4; }
.intro-modal-start:disabled {
  background: #b9c7d4;
  box-shadow: 0 4px 0 #9aacba;
  opacity: 0.7;
  cursor: default;
}

.intro-help-btn {
  position: absolute;
  top: clamp(20px, 3.2vh, 34px);
  left: clamp(24px, 4vw, 42px);
  z-index: 5;
  display: inline-flex;
  align-items: center;
  gap: 7px;
  min-height: 40px;
  padding: 8px 16px 8px 12px;
  border: 3px solid #fff;
  border-radius: 999px;
  background: #2f86ff;
  color: #fff;
  font-family: 'Fredoka', 'Nunito', sans-serif;
  font-size: 14px;
  font-weight: 800;
  box-shadow: 0 6px 16px rgb(16 84 115 / 0.28);
  cursor: pointer;
  animation: intro-help-pop 320ms cubic-bezier(0.2, 1.4, 0.35, 1);
}
.intro-help-btn[hidden] { display: none; }
.intro-help-btn:hover { background: #247af4; }
@keyframes intro-help-pop {
  0% { transform: scale(0.4); opacity: 0; }
  60% { transform: scale(1.12); opacity: 1; }
  100% { transform: scale(1); }
}

@media (max-width: 480px) {
  .intro-modal-card { padding: 26px 18px 22px; }
  .intro-demo { gap: 12px; }
  .intro-note-label { font-size: 34px; }
  .intro-staff-panel { max-width: 150px; height: 190px; }
  .intro-nudge-btn { width: 40px; height: 40px; border-radius: 13px; }
  .intro-nudge-btn svg { width: 22px; height: 22px; }
  .intro-nudge-btn.is-check { min-width: 40px; height: 30px; padding: 0 10px; }
  .intro-nudge-btn.is-check svg { width: 15px; height: 15px; }
  .intro-help-btn {
    top: 16px;
    left: 16px;
    min-height: 34px;
    padding: 6px 12px 6px 10px;
    font-size: 12px;
  }
  .intro-help-btn span { display: none; }
}

@media (prefers-reduced-motion: reduce) {
  .staff-note.is-correct .staff-note-body,
  .staff-note.is-done .staff-note-body,
  .staff-note.is-hearing .staff-note-body,
  .staff-note.is-hearing .staff-success-spark,
  .staff-note.is-correct .staff-success-spark,
  .piano-key.is-wrong,
  .piano-key.is-hearing,
  .hear-btn.is-playing,
  .lesson-speaker.is-playing,
  .hear-btn.is-playing .hear-icon,
  .lesson-speaker.is-playing svg,
  .staff-panel.is-hearing { animation: none; }
  .intro-modal-card { transition: none; }
  .intro-help-btn { animation: none; }
}