:root {
  --bg: #080b11;
  --panel: rgba(16, 22, 32, 0.82);
  --panel-strong: #111923;
  --panel-soft: rgba(255, 255, 255, 0.055);
  --line: rgba(255, 255, 255, 0.12);
  --text: #eef4f8;
  --muted: #9eabb8;
  --wood-dark: #211713;
  --wood-mid: #3a241c;
  --fret-wire: rgba(255, 231, 177, 0.45);
  --root: #ff5d6c;
  --third: #ffd166;
  --fifth: #6ce5b1;
  --accent: #66d9ef;
  --accent-2: #b48cff;
  --shadow: 0 24px 80px rgba(0, 0, 0, 0.36);
  --radius: 8px;
  --motion-fast: 160ms;
  --motion-normal: 280ms;
  --motion-slow: 520ms;
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  --ease-soft: cubic-bezier(0.22, 0.61, 0.36, 1);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

@keyframes fade-rise {
  from {
    opacity: 0;
    transform: translateY(28px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes soft-pop {
  from {
    opacity: 0;
    transform: translateY(18px) scale(0.95);
  }
  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

@keyframes root-pulse {
  0%,
  100% {
    box-shadow: 0 0 0 4px rgba(255, 93, 108, 0.18), 0 0 24px rgba(255, 93, 108, 0.2), 0 10px 26px rgba(0, 0, 0, 0.3);
  }
  50% {
    box-shadow: 0 0 0 6px rgba(255, 93, 108, 0.1), 0 0 34px rgba(255, 93, 108, 0.34), 0 10px 26px rgba(0, 0, 0, 0.3);
  }
}

@keyframes piano-root-pulse {
  0%,
  100% {
    box-shadow: inset 0 0 0 4px rgba(255, 93, 108, 0.82), 0 0 28px rgba(255, 93, 108, 0.24);
  }
  50% {
    box-shadow: inset 0 0 0 5px rgba(255, 93, 108, 0.9), 0 0 40px rgba(255, 93, 108, 0.34);
  }
}

@keyframes tone-refresh {
  0% {
    opacity: 0.42;
    transform: scale(0.86);
    filter: brightness(0.9);
  }

  58% {
    opacity: 1;
    transform: scale(1.12);
    filter: brightness(1.18);
  }

  100% {
    opacity: 1;
    transform: scale(1);
    filter: brightness(1);
  }
}

@keyframes key-refresh {
  0% {
    filter: brightness(0.82);
    transform: translateY(5px) scale(0.98);
  }

  58% {
    filter: brightness(1.16);
    transform: translateY(-4px) scale(1.015);
  }

  100% {
    filter: brightness(1);
    transform: translateY(0) scale(1);
  }
}

@keyframes hero-drift {
  from {
    transform: translate3d(-1.5%, -1%, 0);
  }
  to {
    transform: translate3d(1.5%, 1%, 0);
  }
}

body {
  margin: 0;
  min-height: 100vh;
  color: var(--text);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.6;
  background:
    radial-gradient(circle at 12% 8%, rgba(102, 217, 239, 0.16), transparent 24rem),
    radial-gradient(circle at 84% 10%, rgba(180, 140, 255, 0.12), transparent 26rem),
    linear-gradient(145deg, #080b11 0%, #111827 48%, #090d13 100%);
}

a {
  color: inherit;
  text-decoration: none;
}

button,
select,
input {
  font: inherit;
}

.is-hidden {
  display: none !important;
}

.app-shell {
  min-height: 100vh;
}

.language-gate {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 28px;
  position: relative;
  overflow: hidden;
}

.language-gate::before {
  content: "";
  position: absolute;
  inset: auto -12% 12% -12%;
  height: 180px;
  background:
    repeating-linear-gradient(90deg, rgba(255, 255, 255, 0.045) 0 1px, transparent 1px 92px),
    linear-gradient(90deg, rgba(42, 24, 17, 0.76), rgba(64, 38, 27, 0.82), rgba(32, 21, 19, 0.78));
  border-top: 1px solid rgba(255, 231, 177, 0.2);
  border-bottom: 1px solid rgba(0, 0, 0, 0.42);
  transform: rotate(-4deg);
  opacity: 0.68;
}

.language-card {
  position: relative;
  z-index: 1;
  width: min(820px, 100%);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: clamp(28px, 5vw, 52px);
  background: linear-gradient(145deg, rgba(16, 22, 32, 0.92), rgba(11, 16, 24, 0.86));
  box-shadow: var(--shadow);
  backdrop-filter: blur(20px);
  text-align: center;
  animation: soft-pop var(--motion-slow) var(--ease-out) both;
}

.language-card h1 {
  margin-bottom: 18px;
  font-size: clamp(2.8rem, 7vw, 5.8rem);
}

.language-intro {
  max-width: 560px;
  margin: 0 auto 30px;
  color: var(--muted);
}

.language-actions {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
}

.language-button {
  position: relative;
  overflow: hidden;
  min-height: 112px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  display: grid;
  place-items: center;
  gap: 4px;
  color: var(--text);
  background: rgba(255, 255, 255, 0.055);
  cursor: pointer;
  animation: fade-rise var(--motion-slow) var(--ease-out) both;
  transition: transform var(--motion-normal) var(--ease-out), border-color var(--motion-normal) ease, background var(--motion-normal) ease, box-shadow var(--motion-normal) ease;
}

.language-button:nth-child(2) {
  animation-delay: 70ms;
}

.instrument-card::before {
  content: "";
  position: absolute;
  inset: 0;
  opacity: 0.26;
  pointer-events: none;
}

.guitar-card::before {
  background: repeating-linear-gradient(0deg, transparent 0 18px, rgba(255, 231, 177, 0.34) 19px 20px);
}

.piano-card::before {
  background: repeating-linear-gradient(90deg, rgba(255, 255, 255, 0.28) 0 22px, rgba(0, 0, 0, 0.45) 22px 31px, transparent 31px 46px);
}

.instrument-tags {
  position: relative;
  z-index: 1;
  color: var(--third);
  font-size: 0.78rem;
  font-weight: 900;
  letter-spacing: 0;
}

.language-button:hover,
.language-button:focus-visible {
  transform: translateY(-6px);
  border-color: rgba(102, 217, 239, 0.68);
  background: rgba(102, 217, 239, 0.09);
  box-shadow: 0 22px 54px rgba(102, 217, 239, 0.22);
}

.language-button:active {
  transform: translateY(-1px) scale(0.99);
}

.language-button.is-selected {
  border-color: rgba(102, 217, 239, 0.9);
  background: rgba(102, 217, 239, 0.14);
  box-shadow: 0 0 0 4px rgba(102, 217, 239, 0.14), 0 24px 58px rgba(102, 217, 239, 0.2);
  transform: translateY(-2px) scale(0.99);
}

.language-name {
  font-size: 1.35rem;
  font-weight: 900;
}

.language-note {
  color: var(--muted);
  font-size: 0.93rem;
}

.hero {
  min-height: 92vh;
  padding: 24px clamp(18px, 4vw, 64px) 72px;
  display: flex;
  flex-direction: column;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: "";
  position: absolute;
  inset: auto -8% 7% -8%;
  height: 220px;
  background:
    linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.06), transparent),
    repeating-linear-gradient(90deg, rgba(255, 255, 255, 0.05) 0 1px, transparent 1px 88px),
    linear-gradient(90deg, rgba(42, 24, 17, 0.82), rgba(64, 38, 27, 0.88), rgba(32, 21, 19, 0.86));
  border-top: 1px solid rgba(255, 231, 177, 0.22);
  border-bottom: 1px solid rgba(0, 0, 0, 0.45);
  transform: rotate(-3deg);
  opacity: 0.72;
}

.hero::after {
  content: "";
  position: absolute;
  inset: 0;
  background:
    linear-gradient(90deg, rgba(255, 255, 255, 0.035) 1px, transparent 1px),
    linear-gradient(0deg, rgba(255, 255, 255, 0.026) 1px, transparent 1px);
  background-size: 92px 92px;
  mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.7), transparent 76%);
  pointer-events: none;
  animation: hero-drift 18s var(--ease-soft) infinite alternate;
}

.topbar {
  position: relative;
  z-index: 1;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  max-width: 1180px;
  width: 100%;
  margin: 0 auto;
}

.brand {
  width: 42px;
  height: 42px;
  display: grid;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 50%;
  color: var(--accent);
  background: rgba(255, 255, 255, 0.06);
  font-weight: 800;
  letter-spacing: 0;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 18px;
}

.nav-links {
  display: flex;
  flex-wrap: wrap;
  gap: 18px;
  color: var(--muted);
  font-size: 0.94rem;
}

.nav-links a {
  transition: color 180ms ease;
}

.nav-links a:hover,
.nav-links a:focus-visible {
  color: var(--text);
}

.language-toggle {
  min-width: 82px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 8px 12px;
  color: var(--text);
  background: rgba(255, 255, 255, 0.06);
  cursor: pointer;
  font-weight: 800;
  transition: border-color 180ms ease, background 180ms ease, color 180ms ease;
}

.language-toggle:hover,
.language-toggle:focus-visible {
  border-color: rgba(102, 217, 239, 0.6);
  background: rgba(102, 217, 239, 0.1);
  color: #fff;
}

.hero-content {
  position: relative;
  z-index: 1;
  width: min(860px, 100%);
  margin: auto;
  padding: 72px 0 34px;
}

.hero-content .eyebrow,
.hero-content h1,
.hero-content .subtitle,
.hero-content .hero-copy,
.hero-chips,
.hero-actions {
  opacity: 0;
  animation: fade-rise var(--motion-slow) var(--ease-out) both;
}

.hero-content h1 {
  animation-delay: 70ms;
}

.hero-content .subtitle {
  animation-delay: 130ms;
}

.hero-content .hero-copy {
  animation-delay: 190ms;
}

.hero-chips {
  animation-delay: 250ms;
}

.hero-actions {
  animation-delay: 320ms;
}

.eyebrow {
  margin: 0 0 10px;
  color: var(--accent);
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

h1,
h2,
h3,
p {
  margin-top: 0;
}

h1 {
  margin-bottom: 14px;
  font-size: clamp(3rem, 8vw, 6.8rem);
  line-height: 0.98;
  letter-spacing: 0;
  background: linear-gradient(110deg, #ffffff 0%, #66d9ef 44%, #ffd166 82%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

h2 {
  margin-bottom: 14px;
  font-size: clamp(1.9rem, 4vw, 3.3rem);
  line-height: 1.12;
  letter-spacing: 0;
}

h3 {
  margin-bottom: 10px;
  font-size: 1.1rem;
  letter-spacing: 0;
}

.subtitle {
  margin-bottom: 18px;
  color: #d7e2ea;
  font-size: clamp(1.05rem, 2.2vw, 1.48rem);
}

.hero-copy {
  max-width: 760px;
  margin-bottom: 18px;
  color: var(--muted);
  font-size: 1.04rem;
}

.hero-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 0 0 28px;
}

.hero-chip {
  border: 1px solid rgba(255, 255, 255, 0.14);
  border-radius: 999px;
  padding: 7px 11px;
  color: #dce8ef;
  background: rgba(255, 255, 255, 0.06);
  font-size: 0.86rem;
  font-weight: 800;
  transition: transform var(--motion-fast) var(--ease-out), border-color var(--motion-fast) ease, background var(--motion-fast) ease;
}

.hero-chip:hover {
  transform: translateY(-3px);
  border-color: rgba(102, 217, 239, 0.58);
  background: rgba(102, 217, 239, 0.12);
  box-shadow: 0 10px 24px rgba(102, 217, 239, 0.12);
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.primary-button {
  border: 1px solid rgba(102, 217, 239, 0.6);
  border-radius: var(--radius);
  padding: 13px 19px;
  color: #071015;
  background: linear-gradient(135deg, var(--accent), #8ff7c6);
  box-shadow: 0 14px 34px rgba(102, 217, 239, 0.22);
  cursor: pointer;
  font-weight: 800;
  transition: transform var(--motion-normal) var(--ease-out), box-shadow var(--motion-normal) ease, filter var(--motion-normal) ease;
}

.primary-button:hover,
.primary-button:focus-visible {
  transform: translateY(-2px);
  box-shadow: 0 18px 44px rgba(102, 217, 239, 0.3);
  filter: saturate(1.08);
}

.secondary-hero-button {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 13px 17px;
  color: var(--text);
  background: rgba(255, 255, 255, 0.06);
  cursor: pointer;
  font-weight: 800;
  transition: transform 180ms ease, border-color 180ms ease, background 180ms ease;
}

.secondary-hero-button:hover,
.secondary-hero-button:focus-visible {
  transform: translateY(-2px);
  border-color: rgba(102, 217, 239, 0.55);
  background: rgba(102, 217, 239, 0.09);
}

.section {
  width: min(1180px, calc(100% - 36px));
  margin: 0 auto;
  padding: 78px 0;
}

.section-heading {
  max-width: 760px;
  margin-bottom: 28px;
}

.concept-grid,
.beginner-grid,
.tips-grid,
.learning-path-grid,
.scale-guide-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 18px;
}

.tips-grid,
.scale-guide-grid {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

.info-card,
.beginner-intro-card,
.beginner-card,
.tip-card,
.path-card,
.scale-card,
.control-panel,
.mode-explanation,
.fretboard-shell,
.piano-shell,
.shape-explanation {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
  box-shadow: var(--shadow);
  backdrop-filter: blur(18px);
}

.info-card,
.beginner-card,
.tip-card,
.path-card,
.scale-card {
  position: relative;
  padding: 22px;
  transition: transform var(--motion-normal) var(--ease-out), border-color var(--motion-normal) ease, background var(--motion-normal) ease, box-shadow var(--motion-normal) ease;
}

.info-card:hover,
.beginner-card:hover,
.tip-card:hover,
.path-card:hover,
.scale-card:hover {
  transform: translateY(-6px);
  border-color: rgba(102, 217, 239, 0.52);
  background: rgba(18, 27, 39, 0.88);
  box-shadow: 0 28px 80px rgba(0, 0, 0, 0.44), 0 0 32px rgba(102, 217, 239, 0.08);
}

.info-card p,
.beginner-card p,
.tip-card p,
.path-card p,
.scale-card p,
.shape-copy {
  color: var(--muted);
}

.beginner-section {
  padding-top: 28px;
}

.beginner-intro-card {
  padding: 24px;
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 20px;
}

.beginner-intro-card .section-heading {
  margin-bottom: 0;
}

.beginner-title-row {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
}

.beginner-title-row h2 {
  margin: 0;
}

.optional-badge {
  border: 1px solid rgba(255, 209, 102, 0.34);
  border-radius: 999px;
  padding: 5px 9px;
  color: var(--third);
  background: rgba(255, 209, 102, 0.08);
  font-size: 0.72rem;
  font-weight: 900;
}

.beginner-toggle {
  flex: 0 0 auto;
  border: 1px solid rgba(102, 217, 239, 0.5);
  border-radius: var(--radius);
  padding: 12px 16px;
  color: #071015;
  background: linear-gradient(135deg, var(--accent), #8ff7c6);
  box-shadow: 0 14px 34px rgba(102, 217, 239, 0.18);
  cursor: pointer;
  font-weight: 850;
  transition: transform var(--motion-normal) var(--ease-out), box-shadow var(--motion-normal) ease, filter var(--motion-normal) ease;
}

.beginner-toggle:hover,
.beginner-toggle:focus-visible {
  transform: translateY(-3px);
  box-shadow: 0 20px 48px rgba(102, 217, 239, 0.26);
  filter: saturate(1.08);
  outline: none;
}

.beginner-content {
  margin-top: 18px;
  overflow: hidden;
  opacity: 0;
  transform: translateY(18px);
  transition: opacity var(--motion-slow) var(--ease-out), transform var(--motion-slow) var(--ease-out);
}

.beginner-content.is-expanded {
  opacity: 1;
  transform: translateY(0);
}

.beginner-card {
  min-height: 100%;
}

.beginner-subsection {
  margin-top: 30px;
}

.beginner-subsection-heading {
  margin-bottom: 16px;
}

.beginner-subsection-heading h3 {
  margin: 0;
  font-size: clamp(1.15rem, 2.4vw, 1.6rem);
}

.visual-grid,
.staff-grid {
  align-items: stretch;
}

.beginner-example {
  margin-top: 16px;
  display: grid;
  gap: 7px;
  border: 1px solid rgba(102, 217, 239, 0.18);
  border-radius: var(--radius);
  padding: 12px;
  background: rgba(5, 10, 16, 0.36);
}

.beginner-example-label {
  color: var(--accent);
  font-size: 0.72rem;
  font-weight: 900;
  text-transform: uppercase;
}

.beginner-example code {
  display: block;
  color: #edf8fb;
  background: rgba(255, 255, 255, 0.055);
  border-radius: 6px;
  padding: 7px 9px;
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  font-size: 0.86rem;
  white-space: pre-wrap;
}

.mini-keyboard,
.instrument-mini-demo,
.staff-diagram,
.staff-names,
.middle-c-demo,
.note-values-demo {
  margin-top: 16px;
  border: 1px solid rgba(102, 217, 239, 0.18);
  border-radius: var(--radius);
  padding: 14px;
  background: rgba(5, 10, 16, 0.38);
}

.mini-keyboard {
  position: relative;
  min-height: 132px;
}

.mini-white-keys {
  display: grid;
  grid-template-columns: repeat(7, 1fr);
  min-height: 88px;
  overflow: hidden;
  border-radius: 7px;
}

.mini-white-key {
  display: flex;
  align-items: flex-end;
  justify-content: center;
  border-right: 1px solid rgba(0, 0, 0, 0.24);
  padding-bottom: 8px;
  color: rgba(7, 16, 21, 0.62);
  background: linear-gradient(180deg, #f8fbfc, #d7e0e5);
  font-weight: 900;
}

.mini-white-key:last-child {
  border-right: 0;
}

.mini-white-key.is-highlighted {
  color: #071015;
  background: linear-gradient(180deg, #ff9aa5, var(--root));
  box-shadow: inset 0 0 0 2px rgba(255, 255, 255, 0.46), 0 0 22px rgba(255, 93, 108, 0.26);
}

.mini-black-keys {
  position: absolute;
  left: 14px;
  right: 14px;
  top: 14px;
  height: 54px;
  pointer-events: none;
}

.mini-black-key {
  position: absolute;
  top: 0;
  width: 9%;
  height: 54px;
  display: grid;
  place-items: end center;
  padding-bottom: 5px;
  border-radius: 0 0 5px 5px;
  color: rgba(255, 255, 255, 0.55);
  background: linear-gradient(180deg, #1d2530, #05080d);
  font-size: 0.58rem;
  font-weight: 800;
  box-shadow: 0 8px 18px rgba(0, 0, 0, 0.42);
}

.mini-keyboard strong,
.instrument-mini-demo strong {
  display: block;
  margin-top: 10px;
  color: var(--accent);
  font-size: 0.82rem;
}

.instrument-mini-demo {
  display: grid;
  gap: 14px;
}

.instrument-mini-demo .mini-keyboard {
  margin-top: 0;
}

.mini-fretboard {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  border: 1px solid rgba(255, 231, 177, 0.2);
  border-radius: 7px;
  overflow: hidden;
  background: linear-gradient(100deg, #1b120f, var(--wood-mid), #241712);
}

.mini-fret {
  min-height: 24px;
  display: grid;
  place-items: center;
  border-right: 1px solid rgba(255, 231, 177, 0.22);
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  color: #071015;
  font-size: 0.7rem;
  font-weight: 900;
}

.mini-fret.is-highlighted {
  background: var(--root);
  box-shadow: inset 0 0 0 2px rgba(255, 255, 255, 0.28);
}

.staff-diagram {
  position: relative;
  min-height: 130px;
}

.staff-line {
  position: absolute;
  left: 10%;
  right: 8%;
  height: 1px;
  background: rgba(238, 244, 248, 0.64);
}

.staff-line:nth-child(1) {
  top: 26%;
}

.staff-line:nth-child(2) {
  top: 38%;
}

.staff-line:nth-child(3) {
  top: 50%;
}

.staff-line:nth-child(4) {
  top: 62%;
}

.staff-line:nth-child(5) {
  top: 74%;
}

.staff-note {
  position: absolute;
  z-index: 2;
  width: 24px;
  height: 18px;
  display: grid;
  place-items: center;
  border-radius: 50%;
  color: #071015;
  background: var(--third);
  font-size: 0.66rem;
  font-weight: 950;
  transform: rotate(-16deg);
  box-shadow: 0 0 18px rgba(255, 209, 102, 0.22);
}

.treble-clef {
  position: absolute;
  left: 13%;
  top: 10%;
  color: var(--accent);
  font-size: 4.4rem;
  line-height: 1;
  text-shadow: 0 0 26px rgba(102, 217, 239, 0.24);
}

.bass-clef {
  position: absolute;
  left: 14%;
  top: 23%;
  color: var(--accent);
  font-size: 3.5rem;
  line-height: 1;
  text-shadow: 0 0 26px rgba(102, 217, 239, 0.24);
}

.staff-names {
  display: grid;
  gap: 10px;
}

.staff-names .staff-diagram {
  margin-top: 0;
}

.staff-names code {
  border-radius: 6px;
  padding: 8px 10px;
  color: #edf8fb;
  background: rgba(255, 255, 255, 0.055);
  font-size: 0.82rem;
}

.middle-c-demo {
  display: grid;
  gap: 14px;
}

.middle-c-demo .mini-keyboard,
.middle-c-demo .staff-diagram {
  margin-top: 0;
}

.middle-c-staff::after {
  content: "";
  position: absolute;
  left: 32%;
  top: 89%;
  width: 36px;
  height: 1px;
  background: rgba(238, 244, 248, 0.72);
}

.note-values-demo {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
}

.note-value {
  min-height: 86px;
  display: grid;
  place-items: center;
  gap: 8px;
  border-radius: 7px;
  background: rgba(255, 255, 255, 0.055);
}

.note-value i {
  width: 28px;
  height: 22px;
  border: 2px solid var(--accent);
  border-radius: 50%;
}

.note-value-2 i,
.note-value-3 i {
  position: relative;
}

.note-value-2 i::after,
.note-value-3 i::after {
  content: "";
  position: absolute;
  left: 24px;
  bottom: 12px;
  width: 2px;
  height: 42px;
  background: var(--accent);
}

.note-value-3 i {
  background: var(--accent);
}

.note-value b {
  color: var(--muted);
  font-size: 0.72rem;
}

.piano-range-demo,
.symbol-strip {
  margin-top: 16px;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
  border: 1px solid rgba(102, 217, 239, 0.18);
  border-radius: var(--radius);
  padding: 14px;
  background: rgba(5, 10, 16, 0.38);
}

.range-key,
.symbol-pill {
  min-height: 70px;
  display: grid;
  place-items: center;
  border-radius: 7px;
  color: var(--muted);
  background: rgba(255, 255, 255, 0.055);
  font-weight: 900;
}

.range-key.is-highlighted {
  color: #071015;
  background: var(--root);
  box-shadow: 0 0 22px rgba(255, 93, 108, 0.24);
}

.signature-mark,
.time-signature {
  position: absolute;
  z-index: 3;
  color: var(--third);
  font-weight: 950;
}

.signature-mark {
  font-size: 1.6rem;
}

.time-signature {
  left: 28%;
  top: 28%;
  line-height: 0.82;
  font-size: 2rem;
}

.symbol-pill {
  min-height: 82px;
  gap: 4px;
}

.symbol-pill b {
  color: var(--accent);
  font-size: 1.6rem;
  line-height: 1;
}

.symbol-pill small {
  color: var(--muted);
  font-size: 0.72rem;
  text-align: center;
}

.keyboard-staff-explorer {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 18px;
  background: var(--panel);
  box-shadow: var(--shadow);
}

.explorer-controls {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
  margin-bottom: 16px;
}

.explorer-field {
  display: grid;
  gap: 7px;
  color: var(--muted);
  font-size: 0.8rem;
  font-weight: 900;
}

.explorer-field select {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 10px 11px;
  color: var(--text);
  background: rgba(255, 255, 255, 0.07);
}

.explorer-range-note {
  margin: -4px 0 16px;
  color: var(--muted);
  font-size: 0.82rem;
}

.explorer-body {
  display: grid;
  grid-template-columns: minmax(0, 1.3fr) minmax(280px, 0.9fr);
  gap: 16px;
}

.explorer-keyboard {
  grid-column: 1 / -1;
  display: flex;
  align-items: stretch;
  gap: 2px;
  overflow-x: auto;
  padding: 12px;
  border: 1px solid rgba(102, 217, 239, 0.16);
  border-radius: var(--radius);
  background: rgba(5, 10, 16, 0.38);
}

.explorer-key {
  flex: 0 0 42px;
  min-height: 120px;
  border: 0;
  border-radius: 0 0 6px 6px;
  cursor: pointer;
  font-size: 0.72rem;
  font-weight: 900;
  transition: transform var(--motion-fast) var(--ease-out), box-shadow var(--motion-fast) ease, filter var(--motion-fast) ease;
}

.explorer-keyboard.is-full .explorer-key {
  flex-basis: 24px;
  font-size: 0.58rem;
}

.explorer-key.explorer-white-key {
  color: rgba(7, 16, 21, 0.68);
  background: linear-gradient(180deg, #fbfdff, #d7e0e5);
}

.explorer-key.explorer-black-key {
  min-height: 82px;
  color: rgba(255, 255, 255, 0.72);
  background: linear-gradient(180deg, #1d2530, #05080d);
}

.explorer-key:hover,
.explorer-key:focus-visible,
.explorer-key.is-selected {
  z-index: 2;
  transform: translateY(-4px);
  outline: none;
  filter: saturate(1.08);
}

.explorer-key.is-selected {
  color: #071015;
  background: linear-gradient(180deg, #ff9aa5, var(--root));
  box-shadow: 0 0 26px rgba(255, 93, 108, 0.28);
}

.grand-staff-view {
  display: grid;
  gap: 14px;
}

.explorer-staff-block {
  position: relative;
  min-height: 160px;
  border: 1px solid rgba(102, 217, 239, 0.16);
  border-radius: var(--radius);
  background: rgba(5, 10, 16, 0.38);
}

.explorer-staff-block .staff-line {
  left: 12%;
  right: 8%;
}

.explorer-staff-block .staff-line:nth-of-type(2) {
  top: 26%;
}

.explorer-staff-block .staff-line:nth-of-type(3) {
  top: 38%;
}

.explorer-staff-block .staff-line:nth-of-type(4) {
  top: 50%;
}

.explorer-staff-block .staff-line:nth-of-type(5) {
  top: 62%;
}

.explorer-staff-block .staff-line:nth-of-type(6) {
  top: 74%;
}

.explorer-clef {
  left: 5%;
}

.explorer-note {
  min-width: 28px;
}

.note-accidental {
  position: absolute;
  left: calc(58% - 28px);
  z-index: 3;
  color: var(--accent);
  font-size: 1.15rem;
  font-weight: 950;
  transform: translateY(-18%);
}

.ledger-line {
  position: absolute;
  left: calc(58% - 10px);
  width: 42px;
  height: 1px;
  background: rgba(238, 244, 248, 0.76);
}

.staff-range-warning {
  position: absolute;
  left: 16px;
  right: 16px;
  bottom: 10px;
  color: var(--third);
  font-size: 0.72rem;
  font-weight: 850;
}

.explorer-info {
  border: 1px solid rgba(102, 217, 239, 0.16);
  border-radius: var(--radius);
  padding: 16px;
  background: rgba(5, 10, 16, 0.38);
}

.explorer-info h4 {
  margin: 0 0 10px;
}

.explorer-info p {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  margin: 0;
  padding: 8px 0;
  border-top: 1px solid rgba(255, 255, 255, 0.08);
}

.explorer-info span {
  color: var(--muted);
}

.explorer-info strong {
  color: var(--text);
  text-align: right;
}

.lab-section {
  padding-top: 42px;
}

.control-panel {
  display: grid;
  grid-template-columns: 1fr;
  gap: 18px;
  padding: 20px;
  margin-bottom: 18px;
}

.control-group {
  display: grid;
  gap: 16px;
  padding: 16px;
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: var(--radius);
  background: rgba(255, 255, 255, 0.035);
  transition: border-color var(--motion-normal) ease, background var(--motion-normal) ease;
}

.control-group:focus-within {
  border-color: rgba(102, 217, 239, 0.25);
  background: rgba(102, 217, 239, 0.04);
}

.primary-controls {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.secondary-controls {
  grid-template-columns: minmax(180px, 0.7fr) minmax(200px, 0.8fr) minmax(280px, 1.3fr);
  align-items: end;
}

.audio-controls {
  grid-template-columns: minmax(180px, 0.65fr) minmax(220px, 0.7fr) minmax(240px, 1fr);
  align-items: center;
}

.audio-play-button {
  min-height: 46px;
  border: 1px solid rgba(102, 217, 239, 0.38);
  border-radius: var(--radius);
  padding: 0 16px;
  color: #061017;
  background: linear-gradient(135deg, var(--accent), #9cf0dd);
  font-weight: 950;
  cursor: pointer;
  box-shadow: 0 14px 30px rgba(102, 217, 239, 0.12);
  transition: transform var(--motion-fast) var(--ease-out), box-shadow var(--motion-fast) ease, filter var(--motion-fast) ease;
}

.audio-play-button:hover,
.audio-play-button:focus-visible {
  transform: translateY(-1px);
  filter: brightness(1.05);
  box-shadow: 0 18px 34px rgba(102, 217, 239, 0.2);
  outline: none;
}

.audio-volume-field input {
  width: 100%;
  accent-color: var(--accent);
}

.audio-status {
  margin: 0;
  color: var(--muted);
  font-size: 0.88rem;
}

.mode-explanation {
  padding: 18px 20px;
  margin-bottom: 18px;
}

.mode-explanation h3 {
  margin-bottom: 6px;
}

.mode-explanation p {
  margin-bottom: 0;
  color: var(--muted);
}

.state-pills {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 14px;
}

.state-pill {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  border: 1px solid rgba(255, 255, 255, 0.11);
  border-radius: 999px;
  padding: 6px 10px;
  background: rgba(255, 255, 255, 0.045);
  color: var(--muted);
  font-size: 0.8rem;
  font-weight: 800;
  transition: transform var(--motion-fast) var(--ease-out), border-color var(--motion-fast) ease, background var(--motion-fast) ease;
}

.state-pill:hover {
  transform: translateY(-1px);
  border-color: rgba(102, 217, 239, 0.28);
  background: rgba(102, 217, 239, 0.06);
}

.state-pill strong {
  color: var(--text);
}

.card-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 16px;
}

.card-number {
  color: rgba(102, 217, 239, 0.78);
  font-size: 0.82rem;
  font-weight: 950;
}

.card-label {
  border: 1px solid rgba(255, 209, 102, 0.24);
  border-radius: 999px;
  padding: 4px 8px;
  color: var(--third);
  background: rgba(255, 209, 102, 0.07);
  font-size: 0.72rem;
  font-weight: 900;
}

.field-group {
  display: grid;
  gap: 8px;
}

.field-group label,
.toggle-group legend {
  color: #cbd8e0;
  font-weight: 800;
  font-size: 0.88rem;
}

select {
  width: 100%;
  min-height: 46px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 0 14px;
  color: var(--text);
  background: #0d141d;
  outline: none;
  transition: border-color var(--motion-fast) ease, box-shadow var(--motion-fast) ease, background var(--motion-fast) ease;
}

select:hover,
select:focus-visible {
  border-color: rgba(102, 217, 239, 0.72);
  box-shadow: 0 0 0 4px rgba(102, 217, 239, 0.12);
}

.toggle-group {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 0;
  padding: 0;
  border: 0;
}

.toggle-group legend {
  width: 100%;
  margin-bottom: 2px;
}

.toggle {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  min-height: 38px;
  padding: 8px 11px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  color: var(--muted);
  background: var(--panel-soft);
  cursor: pointer;
  transition: transform var(--motion-fast) var(--ease-out), border-color var(--motion-fast) ease, color var(--motion-fast) ease, background var(--motion-fast) ease;
}

.toggle:hover,
.toggle:focus-within {
  transform: translateY(-1px);
  color: var(--text);
  border-color: rgba(102, 217, 239, 0.5);
  background: rgba(102, 217, 239, 0.08);
}

.toggle:has(input:disabled) {
  cursor: not-allowed;
  opacity: 0.52;
}

.toggle input {
  accent-color: var(--accent);
}

.legend {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  align-items: center;
  margin: 0 0 18px;
  padding: 12px 14px;
  border: 1px solid rgba(255, 255, 255, 0.09);
  border-radius: var(--radius);
  background: rgba(255, 255, 255, 0.035);
}

.legend-title {
  color: #dce8ef;
  font-size: 0.84rem;
  font-weight: 900;
}

.legend-item {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--muted);
  font-size: 0.92rem;
  transition: transform var(--motion-fast) var(--ease-out), color var(--motion-fast) ease;
}

.legend-item:hover {
  transform: translateY(-1px);
  color: var(--text);
}

.legend-dot {
  width: 13px;
  height: 13px;
  border-radius: 50%;
  display: inline-block;
  border: 1px solid rgba(255, 255, 255, 0.4);
}

.legend-dot.root {
  background: var(--root);
}

.legend-dot.third {
  background: var(--third);
}

.legend-dot.fifth {
  background: var(--fifth);
}

.legend-dot.scale {
  background: var(--accent);
}

.legend-dot.other {
  background: rgba(255, 255, 255, 0.18);
}

.fretboard-shell {
  padding: 18px;
  overflow: hidden;
}

.piano-shell {
  padding: 18px;
  overflow: hidden;
}

.fretboard-header {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  align-items: center;
  margin-bottom: 16px;
}

.fretboard-header h3 {
  margin: 0;
}

.shape-badge {
  flex: 0 0 auto;
  border: 1px solid rgba(255, 209, 102, 0.45);
  border-radius: 999px;
  padding: 7px 12px;
  color: var(--third);
  background: rgba(255, 209, 102, 0.08);
  font-weight: 800;
  font-size: 0.88rem;
}

.fretboard-scroll {
  overflow-x: auto;
  overflow-y: hidden;
  padding: 4px 0 12px;
}

.fretboard-scroll:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 4px;
}

.piano-scroll {
  overflow-x: auto;
  overflow-y: hidden;
  padding: 4px 0 12px;
}

.piano-scroll:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 4px;
}

.piano-keyboard {
  position: relative;
  min-width: 980px;
  height: 230px;
  border: 1px solid rgba(255, 255, 255, 0.16);
  border-radius: var(--radius);
  overflow: hidden;
  background:
    linear-gradient(90deg, transparent calc(50% - 1px), rgba(102, 217, 239, 0.18) calc(50% - 1px) calc(50% + 1px), transparent calc(50% + 1px)),
    linear-gradient(145deg, rgba(10, 14, 22, 0.98), rgba(18, 25, 36, 0.92));
}

.piano-keyboard::before,
.piano-keyboard::after {
  position: absolute;
  top: 10px;
  z-index: 4;
  color: rgba(238, 244, 248, 0.48);
  font-size: 0.72rem;
  font-weight: 900;
  pointer-events: none;
}

.piano-keyboard::before {
  content: "C3-B3";
  left: 14px;
}

.piano-keyboard::after {
  content: "C4-B4";
  left: calc(50% + 14px);
}

.piano-white-layer {
  display: grid;
  grid-template-columns: repeat(14, minmax(64px, 1fr));
  height: 100%;
}

.piano-black-layer {
  position: absolute;
  inset: 0;
  pointer-events: none;
}

.piano-key {
  position: relative;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  align-items: center;
  gap: 6px;
  border: 0;
  font: inherit;
  cursor: pointer;
  transition: transform var(--motion-fast) var(--ease-out), box-shadow var(--motion-normal) ease, border-color var(--motion-fast) ease, background var(--motion-normal) ease, opacity var(--motion-normal) ease;
}

.white-key {
  z-index: 0;
  min-height: 214px;
  padding: 0 6px 18px;
  color: #16202b;
  background: linear-gradient(180deg, #fbfcfe 0%, #e6edf3 52%, #c7d2de 100%);
  border-right: 1px solid rgba(13, 20, 29, 0.32);
  box-shadow: inset 0 -18px 28px rgba(0, 0, 0, 0.12), inset 0 1px 0 rgba(255, 255, 255, 0.9);
}

.black-key {
  position: absolute;
  top: 0;
  z-index: 4;
  width: 36px;
  height: 142px;
  padding: 0 4px 13px;
  color: #eef4f8;
  background: linear-gradient(180deg, #252c38 0%, #10151d 46%, #040609 100%);
  border: 1px solid rgba(255, 255, 255, 0.16);
  border-radius: 0 0 6px 6px;
  box-shadow: 0 14px 24px rgba(0, 0, 0, 0.5), inset 0 1px 0 rgba(255, 255, 255, 0.14);
  pointer-events: auto;
}

.white-key:hover,
.white-key:focus-visible {
  z-index: 1;
  transform: translateY(-2px);
  outline: none;
}

.black-key:hover,
.black-key:focus-visible {
  z-index: 5;
  transform: translateY(-2px);
  outline: none;
}

.piano-note-label {
  font-size: 0.86rem;
  font-weight: 900;
  line-height: 1;
}

.piano-interval {
  min-width: 28px;
  min-height: 28px;
  display: grid;
  place-items: center;
  border-radius: 999px;
  color: #071015;
  background: rgba(255, 255, 255, 0.78);
  font-size: 0.76rem;
  font-weight: 900;
  animation: fade-rise var(--motion-normal) var(--ease-out) both;
}

.piano-key.is-chord,
.piano-key.is-scale {
  box-shadow: inset 0 0 0 3px rgba(102, 217, 239, 0.42), 0 12px 28px rgba(102, 217, 239, 0.12);
  animation: soft-pop var(--motion-normal) var(--ease-out) both;
}

.piano-key.interval-root {
  box-shadow: inset 0 0 0 4px rgba(255, 93, 108, 0.88), 0 0 34px rgba(255, 93, 108, 0.32);
  animation: soft-pop var(--motion-normal) var(--ease-out) both, piano-root-pulse 2.8s var(--ease-soft) infinite;
}

.piano-key.interval-third {
  box-shadow: inset 0 0 0 4px rgba(255, 209, 102, 0.72), 0 0 24px rgba(255, 209, 102, 0.2);
}

.piano-key.interval-fifth {
  box-shadow: inset 0 0 0 4px rgba(108, 229, 177, 0.72), 0 0 24px rgba(108, 229, 177, 0.18);
}

.piano-key.interval-scale {
  box-shadow: inset 0 0 0 3px rgba(102, 217, 239, 0.64), 0 0 22px rgba(102, 217, 239, 0.18);
}

.piano-key.is-soft-highlight {
  box-shadow: inset 0 0 0 2px rgba(255, 255, 255, 0.24);
}

.piano-key.is-muted .piano-note-label {
  opacity: 0.32;
}

.piano-key.is-hidden .piano-note-label {
  opacity: 0;
}

.piano-keyboard.is-refreshing .piano-key.is-chord,
.piano-keyboard.is-refreshing .piano-key.is-scale {
  animation: key-refresh 680ms var(--ease-out) both;
}

.piano-keyboard.is-refreshing .piano-key.interval-root {
  animation: key-refresh 680ms var(--ease-out) both, piano-root-pulse 2.8s var(--ease-soft) 680ms infinite;
}

.comparison-grid {
  display: grid;
  gap: 14px;
}

.comparison-row {
  display: grid;
  grid-template-columns: 48px repeat(3, minmax(0, 1fr));
  gap: 14px;
  align-items: stretch;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px;
  background: var(--panel);
  box-shadow: var(--shadow);
  transition: transform var(--motion-normal) var(--ease-out), border-color var(--motion-normal) ease, box-shadow var(--motion-normal) ease;
}

.comparison-row:hover {
  transform: translateY(-5px);
  border-color: rgba(102, 217, 239, 0.44);
  box-shadow: 0 28px 80px rgba(0, 0, 0, 0.42), 0 0 28px rgba(102, 217, 239, 0.08);
}

.comparison-cell {
  border-radius: var(--radius);
  padding: 12px;
  background: rgba(255, 255, 255, 0.045);
}

.comparison-cell span {
  display: block;
  margin-bottom: 6px;
  color: var(--accent);
  font-size: 0.75rem;
  font-weight: 900;
  text-transform: uppercase;
}

.comparison-cell p {
  margin: 0;
  color: var(--muted);
}

.comparison-cell.takeaway {
  background: rgba(255, 209, 102, 0.07);
}

.routine-steps {
  position: relative;
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 18px;
}

.routine-steps::before {
  content: "";
  position: absolute;
  left: 10%;
  right: 10%;
  top: 28px;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(102, 217, 239, 0.48), transparent);
}

.routine-step {
  position: relative;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 22px;
  background: var(--panel);
  box-shadow: var(--shadow);
  transition: transform var(--motion-normal) var(--ease-out), border-color var(--motion-normal) ease, box-shadow var(--motion-normal) ease;
}

.routine-step:hover {
  transform: translateY(-6px);
  border-color: rgba(102, 217, 239, 0.44);
  box-shadow: 0 28px 80px rgba(0, 0, 0, 0.42), 0 0 28px rgba(102, 217, 239, 0.08);
}

.routine-number {
  width: 40px;
  height: 40px;
  display: grid;
  place-items: center;
  border: 1px solid rgba(102, 217, 239, 0.38);
  border-radius: 50%;
  margin-bottom: 16px;
  color: var(--accent);
  background: rgba(102, 217, 239, 0.08);
  font-weight: 950;
}

.routine-step p {
  color: var(--muted);
}

.reveal-on-scroll {
  opacity: 0;
  transform: translateY(28px) scale(0.97);
  transition: opacity var(--motion-slow) var(--ease-out), transform var(--motion-slow) var(--ease-out);
}

.reveal-on-scroll.is-revealed {
  opacity: 1;
  transform: translateY(0) scale(1);
}

.reveal-on-scroll:nth-child(2) {
  transition-delay: 100ms;
}

.reveal-on-scroll:nth-child(3) {
  transition-delay: 200ms;
}

.reveal-on-scroll:nth-child(4) {
  transition-delay: 300ms;
}

.reveal-on-scroll:nth-child(5) {
  transition-delay: 400ms;
}

.reveal-on-scroll:nth-child(6) {
  transition-delay: 500ms;
}

.reveal-on-scroll:nth-child(7) {
  transition-delay: 600ms;
}

.reveal-on-scroll:nth-child(8) {
  transition-delay: 700ms;
}

.fretboard {
  min-width: 980px;
  display: grid;
  grid-template-columns: 58px repeat(13, minmax(66px, 1fr));
  border: 1px solid rgba(255, 231, 177, 0.22);
  border-radius: var(--radius);
  overflow: hidden;
  background:
    linear-gradient(90deg, rgba(0, 0, 0, 0.28), transparent 18%),
    repeating-linear-gradient(0deg, rgba(255, 255, 255, 0.026) 0 1px, transparent 1px 42px),
    linear-gradient(100deg, #1b120f, var(--wood-mid), #241712);
}

.fret-number,
.string-label,
.note-cell {
  min-height: 48px;
  display: grid;
  place-items: center;
}

.corner-cell,
.fret-number {
  color: #d9c9aa;
  background: rgba(0, 0, 0, 0.32);
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  font-weight: 800;
}

.string-label {
  color: #f0dfbe;
  background: rgba(0, 0, 0, 0.28);
  border-right: 1px solid rgba(255, 255, 255, 0.14);
  font-weight: 900;
}

.note-cell {
  position: relative;
  min-height: 56px;
  border-left: 2px solid rgba(255, 231, 177, 0.34);
  border-bottom: 1px solid rgba(255, 255, 255, 0.07);
  color: rgba(238, 244, 248, 0.72);
  transition: transform var(--motion-fast) var(--ease-out), background var(--motion-fast) ease, color var(--motion-fast) ease;
}

.note-cell::before {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  top: 50%;
  height: 2px;
  background: linear-gradient(90deg, transparent, rgba(235, 235, 235, 0.5), transparent);
  transform: translateY(-50%);
  opacity: 0.72;
}

.note-cell:nth-child(14n + 2) {
  border-left-width: 5px;
  border-left-color: rgba(231, 213, 178, 0.72);
}

.note-cell:hover {
  z-index: 2;
  color: #fff;
  background: rgba(102, 217, 239, 0.11);
  transform: scale(1.04);
}

.note-content {
  position: relative;
  z-index: 1;
  min-width: 40px;
  min-height: 40px;
  display: grid;
  place-items: center;
  border-radius: 50%;
  padding: 5px;
  transition: transform var(--motion-normal) var(--ease-out), opacity var(--motion-normal) ease, box-shadow var(--motion-normal) ease, background var(--motion-normal) ease;
}

.note-name {
  font-weight: 900;
  line-height: 1;
}

.interval {
  margin-top: 3px;
  display: block;
  font-size: 0.72rem;
  line-height: 1;
  color: rgba(0, 0, 0, 0.68);
  font-weight: 900;
}

.note-cell.is-muted .note-content {
  opacity: 0.13;
}

.note-cell.is-hidden .note-content {
  opacity: 0;
}

.note-cell.is-chord .note-content {
  color: #091016;
  box-shadow: 0 8px 22px rgba(0, 0, 0, 0.28);
  animation: soft-pop var(--motion-normal) var(--ease-out) both;
}

.note-cell.is-scale .note-content {
  color: #071015;
  background: rgba(102, 217, 239, 0.92);
  box-shadow: 0 8px 22px rgba(0, 0, 0, 0.24);
  animation: soft-pop var(--motion-normal) var(--ease-out) both;
}

.note-cell.interval-root .note-content {
  background: var(--root);
  transform: scale(1.08);
  box-shadow: 0 0 0 4px rgba(255, 93, 108, 0.2), 0 0 28px rgba(255, 93, 108, 0.24), 0 10px 26px rgba(0, 0, 0, 0.32);
  animation: soft-pop var(--motion-normal) var(--ease-out) both, root-pulse 2.8s var(--ease-soft) infinite;
}

.note-cell.interval-third .note-content {
  background: var(--third);
}

.note-cell.interval-fifth .note-content {
  background: var(--fifth);
}

.note-cell.interval-scale .note-content {
  background: rgba(102, 217, 239, 0.92);
}

.note-cell.is-soft-highlight .note-content {
  color: rgba(238, 244, 248, 0.86);
  background: rgba(255, 255, 255, 0.12);
  box-shadow: none;
  transform: none;
}

.fretboard.is-refreshing .note-cell.is-chord .note-content,
.fretboard.is-refreshing .note-cell.is-scale .note-content {
  animation: tone-refresh 680ms var(--ease-out) both;
}

.fretboard.is-refreshing .note-cell.interval-root .note-content {
  animation: tone-refresh 680ms var(--ease-out) both, root-pulse 2.8s var(--ease-soft) 680ms infinite;
}

.note-cell.shape-zone {
  background: rgba(255, 209, 102, 0.045);
}

.note-cell.shape-zone::after {
  content: "";
  position: absolute;
  inset: 7px 5px;
  border: 1px solid rgba(255, 209, 102, 0.16);
  border-radius: 6px;
  pointer-events: none;
}

.shape-explanation {
  margin-top: 18px;
  padding: 22px;
  display: grid;
  grid-template-columns: minmax(190px, 0.7fr) minmax(0, 1.7fr);
  gap: 18px;
}

.shape-explanation p:last-child {
  margin-bottom: 0;
}

.shape-copy strong {
  color: #dce8ef;
}

.footer {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 12px 20px;
  padding: 34px 18px 46px;
  color: var(--muted);
  border-top: 1px solid var(--line);
  background: rgba(0, 0, 0, 0.18);
}

.footer p {
  margin: 0;
}

@media (max-width: 920px) {
  .concept-grid,
  .tips-grid,
  .shape-explanation {
    grid-template-columns: 1fr;
  }

  .tips-grid,
  .beginner-grid,
  .learning-path-grid,
  .scale-guide-grid,
  .routine-steps {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .comparison-row {
    grid-template-columns: 1fr;
  }

  .routine-steps::before {
    display: none;
  }

  .primary-controls,
  .secondary-controls {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .audio-controls {
    grid-template-columns: 1fr;
  }

  .toggle-group {
    grid-column: 1 / -1;
  }
}

@media (max-width: 640px) {
  .language-actions {
    grid-template-columns: 1fr;
  }

  .language-button {
    min-height: 96px;
  }

  .hero {
    min-height: auto;
    padding: 18px 18px 58px;
  }

  .topbar {
    align-items: flex-start;
  }

  .nav-actions {
    align-items: flex-end;
    flex-direction: column-reverse;
    gap: 10px;
  }

  .nav-links {
    gap: 10px;
    font-size: 0.86rem;
  }

  .hero-content {
    padding-top: 72px;
  }

  .section {
    width: min(100% - 28px, 1180px);
    padding: 56px 0;
  }

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

  .beginner-grid,
  .learning-path-grid,
  .scale-guide-grid,
  .routine-steps {
    grid-template-columns: 1fr;
  }

  .beginner-intro-card {
    align-items: stretch;
    flex-direction: column;
  }

  .note-values-demo {
    grid-template-columns: 1fr;
  }

  .piano-range-demo,
  .symbol-strip,
  .explorer-controls,
  .explorer-body {
    grid-template-columns: 1fr;
  }

  .explorer-key {
    flex-basis: 38px;
  }

  .explorer-keyboard.is-full .explorer-key {
    flex-basis: 22px;
  }

  .treble-clef {
    font-size: 3.7rem;
  }

  .primary-controls,
  .secondary-controls {
    grid-template-columns: 1fr;
  }

  .audio-controls {
    grid-template-columns: 1fr;
  }

  .hero-actions {
    align-items: stretch;
    flex-direction: column;
  }

  .control-panel,
  .mode-explanation,
  .fretboard-shell,
  .piano-shell,
  .shape-explanation,
  .info-card,
  .beginner-intro-card,
  .beginner-card,
  .tip-card,
  .path-card,
  .scale-card,
  .comparison-row,
  .routine-step {
    padding: 16px;
  }

  .fretboard-header {
    align-items: flex-start;
    flex-direction: column;
  }

  .fretboard {
    min-width: 890px;
    grid-template-columns: 50px repeat(13, 64px);
  }

  .piano-keyboard {
    min-width: 860px;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
  }
}