/* ==========================================================================
   Chord Explorer — Premium dark theme
   ========================================================================== */

:root {
  /* Background & surface */
  --bg-base: #050816;
  --bg-gradient-start: #0d1430;
  --bg-gradient-end: #02040b;
  --surface: rgba(12, 18, 42, 0.74);
  --surface-border: rgba(162, 181, 255, 0.14);
  --surface-hover: rgba(130, 155, 255, 0.08);

  /* Text */
  --text-primary: #eef3ff;
  --text-secondary: #a7b4db;
  --text-muted: #7280aa;
  --soft: rgba(255, 255, 255, 0.78);
  --indigo: #6366f1;
  --indigo-strong: #4f46e5;

  /* Accent & glow */
  --accent: #77a8ff;
  --accent-soft: rgba(119, 168, 255, 0.22);
  --glow: rgba(119, 168, 255, 0.2);
  --glow-cyan: rgba(165, 198, 255, 0.18);
  --selected-bg: rgba(119, 168, 255, 0.16);
  --selected-ring: rgba(119, 168, 255, 0.34);

  /* Fretboard */
  --fretboard-bg: #2b3240;
  --fretboard-grain-1: rgba(14, 18, 34, 0.34);
  --fretboard-grain-2: rgba(93, 109, 160, 0.14);
  --fretboard-depth: linear-gradient(180deg, rgba(205, 220, 255, 0.14), rgba(32, 39, 52, 0.28));
  --fret-line: rgba(216, 220, 232, 0.22);
  --nut-line: rgba(255, 245, 220, 0.45);
  --string-line: rgba(210, 216, 232, 0.95);
  --marker-bg: #4e73d9;
  --marker-text: #eef4ff;
  --marker-root: #6a90ff;
  --marker-root-glow: rgba(110, 145, 255, 0.42);
  --marker-scale: rgba(110, 145, 255, 0.18);
  --marker-inactive: rgba(57, 68, 103, 0.62);
  --marker-scale-bg: #4e73d9;
  --marker-scale-glow: rgba(110, 145, 255, 0.42);
  --marker-inactive-bg: rgba(49, 42, 58, 0.62);
  --marker-inactive-opacity: 0.78;

  /* Inputs */
  --input-bg: rgba(13, 18, 38, 0.5);
  --input-hover-border: rgba(160, 179, 255, 0.24);

  /* Header title gradient */
  --header-title-from: #ffffff;
  --header-title-to: #9cbcff;

  /* Toggle */
  --toggle-track-bg: rgba(255, 255, 255, 0.12);
  --toggle-thumb-bg: #eef4ff;
  --toggle-thumb-pos: 0;
  --selector-list-bg: rgba(10, 16, 36, 0.52);

  /* Spacing & layout */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 2.5rem;
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 14px;
  --radius-xl: 18px;
  --string-gutter: 88px;

  /* Typography */
  --font-sans: "DM Sans", -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, monospace;

  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-normal: 0.25s ease;
  --shadow-soft: 0 12px 32px rgba(0, 0, 0, 0.34);
  --shadow-glow: 0 0 20px var(--glow);
}

[hidden] {
  display: none !important;
}

/* Light theme */
[data-theme="light"] {
  --bg-base: #fcf8f1;
  --bg-gradient-start: #fffdf9;
  --bg-gradient-end: #f2ebe0;
  --surface: rgba(255, 250, 242, 0.92);
  --surface-border: rgba(117, 82, 46, 0.14);
  --surface-hover: rgba(135, 96, 56, 0.06);

  --text-primary: #402b18;
  --text-secondary: #73553a;
  --text-muted: #8d7154;

  --accent: #9d6536;
  --accent-soft: rgba(157, 101, 54, 0.18);
  --selected-bg: rgba(157, 101, 54, 0.12);
  --selected-ring: rgba(157, 101, 54, 0.28);

  --fretboard-bg: #ffffff;
  --fretboard-grain-1: rgba(122, 83, 44, 0.08);
  --fretboard-grain-2: rgba(255, 248, 225, 0.2);
  --fretboard-depth: linear-gradient(180deg, rgba(255, 242, 210, 0.55), rgba(187, 137, 79, 0.2));
  --fret-line: rgba(102, 67, 33, 0.28);
  --nut-line: rgba(80, 58, 37, 0.4);
  --string-line: rgba(173, 171, 163, 0.95);
  --marker-scale-bg: #83502e;
  --marker-scale-glow: rgba(131, 80, 46, 0.26);
  --marker-inactive-bg: rgba(139, 104, 68, 0.34);
  --marker-inactive-opacity: 0.72;

  --input-bg: rgba(133, 95, 55, 0.07);
  --input-hover-border: rgba(121, 84, 48, 0.24);

  --header-title-from: #654124;
  --header-title-to: #c18649;

  --toggle-track-bg: rgba(110, 74, 43, 0.16);
  --toggle-thumb-bg: #fff4e3;
  --toggle-thumb-pos: 1;
  --selector-list-bg: rgba(255, 248, 238, 0.72);
  --shadow-soft: 0 12px 32px rgba(73, 46, 18, 0.12);
}

html:not([data-theme="light"]) .fretboard__strings .string-ctrl {
  color: #ffffff;
  background: #18234b;
  border-color: rgba(220, 233, 255, 0.72);
  font-size: 0.95rem;
  font-weight: 700;
  text-shadow: 0 1px 0 rgba(0, 0, 0, 0.45);
  box-shadow: 0 0 0 1px rgba(120, 164, 255, 0.18), 0 3px 10px rgba(0, 0, 0, 0.42);
}

html:not([data-theme="light"]) .fretboard__strings .string-ctrl:hover {
  color: #ffffff;
  background: #22305f;
  border-color: rgba(242, 247, 255, 0.9);
}

[data-theme="light"] .fretboard__strings .string-ctrl {
  color: #fffaf2;
  background: #6c4726;
  border-color: rgba(92, 58, 27, 0.78);
  font-size: 0.95rem;
  font-weight: 700;
  text-shadow: 0 1px 0 rgba(0, 0, 0, 0.3);
  box-shadow: 0 1px 0 rgba(255, 255, 255, 0.12), 0 2px 6px rgba(72, 43, 16, 0.2);
}

[data-theme="light"] .fretboard__strings .string-ctrl:hover {
  color: #ffffff;
  background: #7d5430;
  border-color: rgba(79, 48, 21, 0.9);
}

/* Reset & base */
*, *::before, *::after { box-sizing: border-box; }
html {
  font-size: 16px;
  scroll-behavior: smooth;
  overflow-x: hidden;
}
body {
  margin: 0;
  min-height: 100vh;
  font-family: var(--font-sans);
  font-weight: 400;
  color: var(--text-primary);
  background: #000000;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  position: relative;
  overflow-x: hidden;
}

.background {
  position: fixed;
  inset: 0;
  z-index: 0;
  overflow: hidden;
  pointer-events: none;
}

.sky-gradient {
  position: absolute;
  inset: 0;
  background:
    radial-gradient(circle at 18% 18%, rgba(45, 212, 191, 0.18), transparent 24rem),
    radial-gradient(circle at 82% 16%, rgba(168, 85, 247, 0.18), transparent 24rem),
    linear-gradient(180deg, #000000 0%, #101014 48%, #000000 100%);
}

.star {
  position: absolute;
  width: var(--size);
  height: var(--size);
  top: var(--top);
  left: var(--left);
  border-radius: 999px;
  background: #fff;
  opacity: 0.78;
  animation: twinkle var(--duration) ease-in-out infinite;
  animation-delay: var(--delay);
}

.shooting-star {
  position: absolute;
  width: 2px;
  height: 120px;
  top: var(--top);
  right: var(--right);
  border-radius: 999px;
  background: linear-gradient(to bottom, rgba(255, 255, 255, 0.92), transparent);
  filter: drop-shadow(0 0 8px rgba(255, 255, 255, 0.6));
  transform: rotate(-135deg);
  animation: shoot 5.5s ease-out forwards;
}

[data-theme="light"] body {
  background:
    radial-gradient(circle at top, rgba(214, 171, 110, 0.1), transparent 32%),
    linear-gradient(165deg, var(--bg-gradient-start) 0%, var(--bg-gradient-end) 100%);
}

[data-theme="light"] body::before {
  display: none;
}

.app,
.header,
.card,
.fretboard {
  position: relative;
  z-index: 1;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* App shell */
.app {
  max-width: 1200px;
  margin: 0 auto;
  padding: var(--space-xl) var(--space-lg) var(--space-lg);
  display: flex;
  flex-direction: column;
  gap: var(--space-xl);
}

/* Shared header */
.site-header {
  position: sticky;
  top: 0;
  left: 0;
  z-index: 3;
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.85rem 1.5rem;
  background: rgba(3, 7, 18, 0.76);
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  backdrop-filter: blur(16px);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: normal;
}

.site-header a,
.site-header button {
  border: 0;
  font: inherit;
  letter-spacing: 0;
}

.account-bar {
  position: static;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}
.account-menu-wrap {
  position: relative;
}
.account-link {
  color: var(--soft);
  font-size: 0.9rem;
  font-weight: 700;
  text-decoration: none;
}
.account-link:hover {
  color: #fff;
}
.account-email {
  max-width: 14rem;
  overflow: hidden;
  color: var(--soft);
  font-size: 0.86rem;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.account-menu-button {
  appearance: none;
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  max-width: 18rem;
  min-height: 2.25rem;
  padding: 0.45rem 0.4rem 0.45rem 0;
  border: 0;
  border-radius: 999px;
  color: var(--soft);
  background: transparent;
  cursor: pointer;
  transition: color 180ms ease, background 180ms ease;
}
.account-menu-button:hover,
.account-menu-button[aria-expanded="true"] {
  color: #fff;
  background: rgba(255, 255, 255, 0.08);
}
.account-menu-arrow {
  width: 1rem;
  height: 1rem;
  flex: 0 0 auto;
  transition: transform 180ms ease;
}
.account-menu-button[aria-expanded="true"] .account-menu-arrow {
  transform: rotate(180deg);
}
.account-menu {
  position: absolute;
  top: calc(100% + 0.55rem);
  right: 0;
  z-index: 8;
  min-width: 12rem;
  padding: 0.45rem;
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: 8px;
  background: rgba(3, 7, 18, 0.96);
  box-shadow: 0 18px 44px rgba(0, 0, 0, 0.4);
  backdrop-filter: blur(16px);
}
.account-menu-link {
  appearance: none;
  width: 100%;
  display: flex;
  align-items: center;
  min-height: 2.4rem;
  padding: 0.45rem 0.65rem;
  border: 0;
  border-radius: 6px;
  color: var(--soft);
  background: transparent;
  font-size: 0.9rem;
  font-weight: 750;
  text-align: left;
  cursor: pointer;
}
.account-menu-link:hover,
.account-menu-link:focus-visible {
  color: #fff;
  background: rgba(255, 255, 255, 0.1);
  outline: 0;
}
.brand-link {
  display: inline-flex;
  align-items: center;
  flex: 0 0 auto;
}
.brand-link img {
  width: auto;
  height: 4.4rem;
}
.mobile-nav-toggle {
  display: none;
}
.primary-nav {
  display: flex;
  flex: 1 1 auto;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 0.35rem;
}
.primary-nav a {
  padding: 0.55rem 0.75rem;
  border-radius: 999px;
  color: var(--soft);
  font-size: 0.92rem;
  font-weight: 750;
  text-decoration: none;
  transition: background 180ms ease, color 180ms ease;
}
.primary-nav a,
.account-link,
.account-button,
.account-menu-button,
.mobile-nav-toggle,
.instrument-toggle button,
.setting-select__trigger,
.entity-select__trigger {
  -webkit-tap-highlight-color: transparent;
}
.primary-nav a:hover,
.primary-nav a[aria-current="page"] {
  color: #fff;
  background: rgba(255, 255, 255, 0.12);
}
.site-header.is-mobile-nav {
  align-items: flex-start;
  flex-direction: column;
  gap: 0.65rem;
}
.site-header.is-mobile-nav .mobile-nav-toggle {
  position: absolute;
  top: 1.25rem;
  right: 1.5rem;
  width: 2.7rem;
  height: 2.7rem;
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.28rem;
  border-radius: 999px;
  color: #fff;
  background: rgba(255, 255, 255, 0.12);
  cursor: pointer;
  transition: background 180ms ease, transform 180ms ease;
}
.site-header.is-mobile-nav .mobile-nav-toggle:hover,
.site-header.is-mobile-nav .mobile-nav-toggle:focus-visible {
  background: rgba(255, 255, 255, 0.2);
  outline: 0;
}
.site-header.is-mobile-nav .mobile-nav-toggle span {
  width: 1.1rem;
  height: 2px;
  border-radius: 999px;
  background: currentColor;
  transition: transform 180ms ease, opacity 180ms ease;
}
.site-header.is-mobile-nav.is-nav-open .mobile-nav-toggle span:nth-child(1) {
  transform: translateY(0.37rem) rotate(45deg);
}
.site-header.is-mobile-nav.is-nav-open .mobile-nav-toggle span:nth-child(2) {
  opacity: 0;
}
.site-header.is-mobile-nav.is-nav-open .mobile-nav-toggle span:nth-child(3) {
  transform: translateY(-0.37rem) rotate(-45deg);
}
.site-header.is-mobile-nav .primary-nav {
  display: none;
  flex-direction: column;
  flex-wrap: nowrap;
  align-items: stretch;
  justify-content: flex-start;
  width: 100%;
  margin: 0;
  padding: 0.45rem;
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: 8px;
  background: rgba(3, 7, 18, 0.76);
  box-shadow: 0 18px 44px rgba(0, 0, 0, 0.28);
}
.site-header.is-mobile-nav .primary-nav a {
  width: 100%;
  padding: 0.7rem 0.8rem;
  border-radius: 6px;
  font-size: 0.92rem;
}
.site-header.is-mobile-nav.is-nav-open .primary-nav {
  display: flex;
}
.site-header.is-mobile-nav .account-bar {
  width: 100%;
  display: none;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 0.55rem;
  min-width: 0;
  margin: -0.25rem 0 0;
  padding: 0.45rem;
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: 8px;
  background: rgba(3, 7, 18, 0.76);
  box-shadow: 0 18px 44px rgba(0, 0, 0, 0.28);
}
.site-header.is-mobile-nav.is-nav-open .account-bar {
  display: flex;
}
.site-header.is-mobile-nav .account-menu-wrap {
  max-width: 100%;
  min-width: 0;
}
.site-header.is-mobile-nav .account-email {
  max-width: min(13rem, 54vw);
}
.site-header.is-mobile-nav .account-menu-button {
  min-width: 0;
}
.site-header.is-mobile-nav .account-menu {
  position: static;
  flex-basis: 100%;
  max-width: calc(100vw - 1.5rem);
  margin-top: 0.45rem;
}
.account-button {
  appearance: none;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 2.25rem;
  padding: 0.45rem 0.85rem;
  border: 0;
  border-radius: 999px;
  color: #fff;
  background: rgba(255, 255, 255, 0.12);
  font-size: 0.9rem;
  font-weight: 750;
  cursor: pointer;
  transition: background 180ms ease, opacity 180ms ease, transform 180ms ease;
}
.account-button:hover {
  background: rgba(255, 255, 255, 0.2);
  transform: translateY(-1px);
}
.account-button:disabled {
  cursor: not-allowed;
  opacity: 0.62;
  transform: none;
}
.account-button.primary {
  background: var(--indigo);
}
.account-button.primary:hover {
  background: var(--indigo-strong);
}

/* Tool header */
.tool-header {
  text-align: center;
}
.tool-header__eyebrow {
  margin: 0 0 0.5rem;
  color: #2dd4bf;
  font-size: 0.78rem;
  font-weight: 850;
  letter-spacing: 0;
  text-transform: uppercase;
}
.tool-header h1 {
  margin: 0 0 0.65rem;
  font-size: clamp(2rem, 5vw, 3.4rem);
  line-height: 1.06;
}
.tool-header p {
  margin: 0 auto;
  max-width: 38rem;
  color: var(--text-secondary);
}
/* Legacy header */
.header {
  text-align: center;
  padding: 0 0 var(--space-xs);
}
.header__top {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: var(--space-lg);
  margin-bottom: var(--space-xs);
}
.header__nav-asset {
  justify-self: start;
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  padding: 0.45rem 0.85rem;
  border: 1px solid var(--surface-border);
  border-radius: 999px;
  background: var(--surface);
  color: var(--text-primary);
  text-decoration: none;
  backdrop-filter: blur(8px);
  box-shadow: var(--shadow-soft);
  transition: transform var(--transition-fast), border-color var(--transition-fast), background var(--transition-fast);
}
.header__nav-asset:hover {
  transform: translateY(-1px);
  border-color: var(--input-hover-border);
  background: var(--surface-hover);
}
.header__nav-asset:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}
.header__nav-label {
  font-size: 0.88rem;
  font-weight: 600;
  line-height: 1;
}
.header__nav-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 2.25rem;
  padding: 0.18rem 0.45rem;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  line-height: 1;
}
.header__title {
  grid-column: 2;
  justify-self: center;
  margin: 0;
}
.header__logo {
  display: block;
  width: auto;
  height: 5rem;
}
.header__nav {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 0.35rem;
  margin-bottom: var(--space-sm);
}
.header__nav a {
  padding: 0.48rem 0.7rem;
  border-radius: 999px;
  color: var(--text-secondary);
  font-size: 0.9rem;
  font-weight: 700;
  text-decoration: none;
  transition: background var(--transition-fast), color var(--transition-fast);
}
.header__nav a:hover {
  color: var(--text-primary);
  background: var(--surface);
}
.header__subtitle {
  margin: 0;
  font-size: 0.95rem;
  color: var(--text-secondary);
  max-width: 480px;
  margin-left: auto;
  margin-right: auto;
}
.header__pill {
  display: inline-block;
  padding: var(--space-xs) var(--space-md);
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--text-primary);
  background: var(--surface);
  border: 1px solid var(--surface-border);
  border-radius: 999px;
  backdrop-filter: blur(8px);
  box-shadow: inset 0 1px 0 rgba(255, 248, 236, 0.5);
}
.header__pill--meta {
  font-size: 0.72rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--text-secondary);
}

.footer {
  width: 100%;
  padding: 40px 0 30px;
  text-align: center;
}

.footer__copy {
  margin: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.65rem;
  flex-wrap: wrap;
  font-family: Inter, system-ui, sans-serif;
  font-size: clamp(12px, 1.15vw, 14px);
  font-weight: 400;
  color: #8b95a7;
}

.footer__separator {
  color: #6f7887;
}

.footer__link {
  color: #8b95a7;
  text-decoration: underline;
  text-underline-offset: 0.15em;
  transition: color var(--transition-fast), text-decoration-color var(--transition-fast);
}

.footer__link:visited,
.footer__link:active {
  color: #8b95a7;
}

.footer__link:hover,
.footer__link:focus-visible {
  color: #cbd5e1;
}

.footer__link:focus-visible {
  outline: none;
}

/* Cards */
.card {
  background: var(--surface);
  border: 1px solid var(--surface-border);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  backdrop-filter: blur(12px);
  box-shadow: var(--shadow-soft);
  position: relative;
  overflow: hidden;
}
.card::before {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, rgba(255, 248, 238, 0.2), transparent 42%);
  pointer-events: none;
}
.card__title {
  margin: 0 0 var(--space-md);
  font-size: 0.85rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-secondary);
}
.card__title--with-icon {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}
.card__title-icon {
  width: 1.25rem;
  height: 1.25rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: var(--accent);
}
.card__title-icon svg {
  width: 100%;
  height: 100%;
  display: block;
}
.card__title-toggle {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-md);
  padding: 0;
  margin: 0;
  border: none;
  background: none;
  color: inherit;
  cursor: pointer;
  text-align: left;
}
.card__title-toggle-content {
  min-width: 0;
  display: flex;
  align-items: center;
  gap: 0.65rem;
}
.card__title-toggle .card__title {
  margin: 0;
  flex-shrink: 0;
}
.card__title-toggle:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 6px;
  border-radius: var(--radius-sm);
}
.card__title-summary {
  font-size: 0.8rem;
  color: var(--text-muted);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  min-width: 0;
}
.card--controls.is-open .card__title-summary {
  display: none;
}
.card__title-toggle-chevron {
  width: 0.7rem;
  height: 0.7rem;
  flex-shrink: 0;
  border-right: 2px solid var(--text-muted);
  border-bottom: 2px solid var(--text-muted);
  transform: rotate(45deg);
  transition: transform var(--transition-fast), border-color var(--transition-fast);
}
.card__title-toggle[aria-expanded="true"] .card__title-toggle-chevron {
  transform: rotate(-135deg);
  border-color: var(--text-primary);
}

/* Top controls card */
.card--controls {
  overflow: visible;
  z-index: 5;
  padding: 0.9rem 1rem;
}
.card--controls.is-open {
  padding: var(--space-lg);
}

.controls-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: var(--space-lg);
  align-items: end;
  margin-top: 0.85rem;
}
.controls-grid[hidden] {
  display: none;
}
.control-group {
  margin: 0;
  min-width: 0;
}
.control-label {
  display: block;
  margin-bottom: var(--space-sm);
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--text-secondary);
}
.setting-select {
  position: relative;
}
.setting-select__trigger {
  width: 100%;
  min-height: 46px;
  padding: 0.75rem 2.75rem 0.75rem 0.95rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-md);
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 600;
  text-align: left;
  color: var(--text-primary);
  background: var(--input-bg);
  border: 1px solid var(--surface-border);
  border-radius: 12px;
  cursor: pointer;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast), background var(--transition-fast), transform var(--transition-fast);
  backdrop-filter: blur(10px);
}
.setting-select__trigger:hover,
.setting-select__trigger:focus-visible,
.setting-select.is-open .setting-select__trigger {
  border-color: var(--input-hover-border);
  box-shadow: 0 0 0 2px var(--accent-soft);
  outline: none;
}
.setting-select__value {
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.setting-select__chevron {
  position: absolute;
  right: 1rem;
  top: 50%;
  width: 0.65rem;
  height: 0.65rem;
  border-right: 2px solid currentColor;
  border-bottom: 2px solid currentColor;
  transform: translateY(-65%) rotate(45deg);
  color: var(--text-muted);
  pointer-events: none;
  transition: transform var(--transition-fast), color var(--transition-fast);
}
.setting-select.is-open .setting-select__chevron {
  transform: translateY(-35%) rotate(-135deg);
  color: var(--text-primary);
}
.setting-select__menu {
  position: absolute;
  top: calc(100% + 0.5rem);
  left: 0;
  right: 0;
  z-index: 30;
  display: grid;
  gap: 0.35rem;
  padding: 0.45rem;
  max-height: 260px;
  overflow-y: auto;
  background: var(--bg-base);
  border: 1px solid var(--input-hover-border);
  border-radius: 14px;
  box-shadow: 0 20px 44px rgba(0, 0, 0, 0.28);
  backdrop-filter: blur(28px);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-6px);
  transition: opacity var(--transition-fast), transform var(--transition-fast), visibility var(--transition-fast);
}
.setting-select.is-open .setting-select__menu {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}
.setting-select[data-setting="tuning"] .setting-select__menu {
  width: min(25.5rem, 52.5vw);
  max-width: none;
}
.setting-select__option {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-md);
  padding: 0.75rem 0.85rem;
  border: 1px solid transparent;
  border-radius: 10px;
  background: transparent;
  color: var(--text-primary);
  font: inherit;
  text-align: left;
  cursor: pointer;
  transition: background var(--transition-fast), border-color var(--transition-fast), transform var(--transition-fast);
}
.setting-select__option:hover,
.setting-select__option:focus-visible {
  background: var(--surface-hover);
  border-color: var(--surface-border);
  outline: none;
}
.setting-select__option[aria-selected="true"] {
  background: var(--selected-bg);
  border-color: var(--selected-ring);
}
.setting-select__option-text {
  min-width: 0;
}
.setting-select__option-check {
  flex-shrink: 0;
  padding: 0.2rem 0.45rem;
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.03em;
  color: var(--accent);
  background: var(--accent-soft);
  border-radius: 999px;
}

/* Fretboard card */
.card--fretboard {
  padding: var(--space-xl) var(--space-xl) var(--space-md);
  overflow-x: auto;
}
.fretboard__status {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 0.4rem;
  flex-wrap: wrap;
  margin-bottom: var(--space-md);
}
.instrument-toggle {
  display: inline-flex;
  align-items: center;
  padding: 0.2rem;
  border: 1px solid var(--surface-border);
  border-radius: 999px;
  background: var(--surface);
  backdrop-filter: blur(8px);
}
.instrument-toggle button {
  min-height: 2rem;
  padding: 0.38rem 0.82rem;
  border: 0;
  border-radius: 999px;
  color: var(--text-secondary);
  background: transparent;
  font: inherit;
  font-size: 0.82rem;
  font-weight: 800;
  cursor: pointer;
}
.instrument-toggle button[aria-pressed="true"] {
  color: #fff;
  background: rgba(119, 168, 255, 0.24);
}
.fretboard__status-slot {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 0;
}
.fretboard__status-slot[hidden],
.fretboard__status-select[hidden] {
  display: none;
}
.fretboard__status-slot--wide {
  min-width: 0;
}
.fretboard-wrap {
  min-width: 0;
  --visible-frets: 13;
}
.fretboard-wrap[hidden],
.keyboard-wrap[hidden] {
  display: none;
}
.fretboard {
  position: relative;
  min-width: 420px;
  max-width: 100%;
  margin: 0 auto;
}
.fretboard__frets-nums {
  display: grid;
  grid-template-columns: var(--string-gutter) repeat(var(--visible-frets), 1fr);
  gap: 0;
  margin-bottom: var(--space-xs);
  padding-left: 0;
  font-size: 0.7rem;
  font-weight: 500;
  color: var(--text-muted);
  text-align: center;
}
.fretboard__frets-nums span:first-child {
  grid-column: 1;
}
.fretboard__nut {
  position: absolute;
  left: calc(var(--string-gutter) + ((100% - var(--string-gutter)) / var(--visible-frets)) - 3px);
  top: 20px;
  bottom: 20px;
  width: 6px;
  background: linear-gradient(90deg, #f4e7cc 0%, #d2b186 100%);
  border-radius: 2px;
  z-index: 2;
  pointer-events: none;
  box-shadow: 0 0 0 1px rgba(83, 55, 31, 0.15), 0 2px 6px rgba(0, 0, 0, 0.18);
}
.fretboard__grid {
  display: grid;
  grid-template-columns: repeat(var(--visible-frets), 1fr);
  grid-template-rows: repeat(6, minmax(44px, 1fr));
  gap: 0;
  margin-left: var(--string-gutter);
  background:
    linear-gradient(90deg, var(--fretboard-grain-1) 0%, transparent 14%, var(--fretboard-grain-2) 28%, transparent 46%, var(--fretboard-grain-1) 62%, transparent 78%, var(--fretboard-grain-2) 100%),
    var(--fretboard-depth),
    var(--fretboard-bg);
  border-radius: var(--radius-md);
  padding: 0;
  border: 1px solid var(--surface-border);
  min-height: 200px;
  box-shadow: inset 0 1px 0 rgba(255, 247, 226, 0.45), inset 0 -10px 22px rgba(117, 76, 38, 0.08);
}
.fretboard__grid .cell {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  border-right: 1px solid var(--fret-line);
}
.fretboard__grid .cell:last-child { border-right: none; }
.fretboard__grid .cell::before {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  top: 50%;
  height: 1px;
  background: var(--string-line);
  pointer-events: none;
}
.fretboard__positions {
  display: grid;
  grid-template-columns: var(--string-gutter) repeat(var(--visible-frets), 1fr);
  gap: 0;
  margin-top: var(--space-sm);
  font-size: 0.7rem;
  color: var(--text-muted);
  text-align: center;
}
.fretboard__strings {
  position: absolute;
  left: 0;
  top: 20px;
  bottom: 20px;
  display: grid;
  grid-template-rows: repeat(6, minmax(44px, 1fr));
  align-items: center;
  padding: 0 4px 0 0;
  width: var(--string-gutter);
  z-index: 1;
}
.fretboard__strings .string-row {
  display: flex;
  align-items: center;
  gap: 4px;
  justify-content: flex-start;
  height: 100%;
}
.fretboard__strings .string-label {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-secondary);
  min-width: 1.2em;
  text-align: center;
}
.fretboard__strings .string-ctrl {
  width: 18px;
  height: 18px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 0.75rem;
  color: var(--text-secondary);
  background: rgba(255, 248, 236, 0.55);
  border: 1px solid var(--surface-border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: color var(--transition-fast), background var(--transition-fast), border-color var(--transition-fast);
}
.fretboard__strings .string-ctrl:hover {
  color: var(--text-primary);
  background: var(--surface-hover);
  border-color: rgba(255,255,255,0.12);
}

/* Note markers on fretboard */
.note-marker {
  position: relative;
  width: 28px;
  height: 28px;
  min-width: 28px;
  min-height: 28px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.7rem;
  font-weight: 600;
  font-family: var(--font-mono);
  color: var(--marker-text);
  border: 1px solid rgba(255, 244, 224, 0.18);
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
  z-index: 1;
}

/* Scale / chord tones: bright electric blue, subtle glow */
.note-marker.note-marker--scale {
  background: var(--marker-scale-bg);
  border-color: rgba(255, 239, 213, 0.24);
  box-shadow: 0 0 8px var(--marker-scale-glow), inset 0 1px 0 rgba(255, 242, 218, 0.18), 0 2px 6px rgba(61, 35, 15, 0.18);
  color: var(--marker-text);
}

/* Root note: same as other scale/chord tones */
.note-marker.note-marker--root {
  background: #9a5e30;
  border-color: rgba(255, 238, 213, 0.28);
  box-shadow: 0 0 10px rgba(159, 103, 54, 0.24), inset 0 1px 0 rgba(255, 243, 221, 0.2), 0 2px 6px rgba(67, 39, 18, 0.22);
  color: #fff8eb;
}

/* Non-scale notes: dim but readable */
.note-marker.note-marker--inactive {
  background: var(--marker-inactive-bg);
  opacity: var(--marker-inactive-opacity);
  color: var(--text-secondary);
}

/* 88-key keyboard */
.keyboard-wrap {
  width: 100%;
}
.keyboard-scroll {
  width: 100%;
  overflow-x: auto;
  padding: 0.75rem 0 0.35rem;
}
.keyboard {
  position: relative;
  width: min(100%, 1080px);
  min-width: 980px;
  height: 15rem;
  margin: 0 auto;
}
.keyboard__white {
  position: absolute;
  inset: 0;
  display: grid;
  grid-template-columns: repeat(52, minmax(0, 1fr));
  gap: 1px;
}
.keyboard__black {
  position: absolute;
  inset: 0;
  pointer-events: none;
}
.piano-key {
  position: relative;
  display: flex;
  align-items: flex-end;
  justify-content: center;
  border-radius: 0 0 6px 6px;
}
.piano-key--white {
  height: 100%;
  background: linear-gradient(180deg, #fff 0%, #dce3ef 100%);
  border: 1px solid rgba(5, 10, 24, 0.22);
  box-shadow: inset 0 -10px 18px rgba(13, 20, 38, 0.1);
}
.piano-key--black {
  position: absolute;
  top: 0;
  z-index: 2;
  width: 1.12rem;
  height: 9.2rem;
  background: linear-gradient(180deg, #171923 0%, #03050a 100%);
  border: 1px solid rgba(255, 255, 255, 0.12);
  box-shadow: 0 9px 16px rgba(0, 0, 0, 0.34);
}
.piano-key.is-active.piano-key--white {
  background: linear-gradient(180deg, #d9e7ff 0%, #88aafc 100%);
  border-color: rgba(96, 132, 255, 0.66);
}
.piano-key.is-active.piano-key--black {
  background: linear-gradient(180deg, #6f8dff 0%, #253783 100%);
}
.piano-key.is-root.piano-key--white {
  background: linear-gradient(180deg, #ffe8c7 0%, #c77b3c 100%);
  border-color: rgba(194, 111, 47, 0.72);
}
.piano-key.is-root.piano-key--black {
  background: linear-gradient(180deg, #d48c4d 0%, #7a3f18 100%);
}
.piano-key__marker {
  max-width: calc(100% - 2px);
  margin-bottom: 0.48rem;
  padding: 0.12rem 0.18rem;
  border-radius: 4px;
  color: #09111f;
  background: rgba(255, 255, 255, 0.72);
  font-family: var(--font-mono);
  font-size: 0.56rem;
  font-weight: 800;
  line-height: 1;
  text-align: center;
  white-space: nowrap;
}
.piano-key--black .piano-key__marker {
  margin-bottom: 0.35rem;
  color: #fff;
  background: rgba(0, 0, 0, 0.28);
  writing-mode: vertical-rl;
}

.selector-panel {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-md);
}
.entity-select {
  position: relative;
}
.fretboard__status-select {
  width: auto;
  min-width: 0;
}
.fretboard__status-slot--wide .fretboard__status-select {
  width: auto;
}
.fretboard__status-select .entity-select__trigger {
  width: auto;
  min-height: 34px;
  min-width: 0;
  padding: 0.45rem 2.3rem 0.45rem 1rem;
  border-radius: 999px;
  font-size: 0.82rem;
  background: var(--surface);
  backdrop-filter: blur(8px);
  box-shadow: inset 0 1px 0 rgba(255, 248, 236, 0.5);
}
.fretboard__status-select .entity-select__menu {
  top: calc(100% + 0.35rem);
}
.entity-select--wide .entity-select__menu {
  width: min(16.8rem, 42vw);
  max-width: none;
}
.entity-select__trigger {
  width: 100%;
  min-height: 48px;
  padding: 0.8rem 2.75rem 0.8rem 0.95rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-md);
  font: inherit;
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-primary);
  text-align: left;
  background: var(--input-bg);
  border: 1px solid var(--surface-border);
  border-radius: 12px;
  cursor: pointer;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast), background var(--transition-fast);
  backdrop-filter: blur(10px);
}
.entity-select__trigger:hover,
.entity-select__trigger:focus-visible,
.entity-select.is-open .entity-select__trigger {
  border-color: var(--input-hover-border);
  box-shadow: 0 0 0 2px var(--accent-soft);
  outline: none;
}
.entity-select__value {
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.entity-select__chevron {
  position: absolute;
  right: 1rem;
  top: 50%;
  width: 0.65rem;
  height: 0.65rem;
  border-right: 2px solid currentColor;
  border-bottom: 2px solid currentColor;
  transform: translateY(-65%) rotate(45deg);
  color: var(--text-muted);
  pointer-events: none;
  transition: transform var(--transition-fast), color var(--transition-fast);
}
.entity-select.is-open .entity-select__chevron {
  transform: translateY(-35%) rotate(-135deg);
  color: var(--text-primary);
}
.entity-select__menu {
  position: absolute;
  top: calc(100% + 0.5rem);
  left: 0;
  right: 0;
  z-index: 30;
  display: grid;
  gap: 0.35rem;
  padding: 0.45rem;
  max-height: 260px;
  overflow-y: auto;
  background: var(--bg-base);
  border: 1px solid var(--input-hover-border);
  border-radius: 14px;
  box-shadow: 0 20px 44px rgba(0, 0, 0, 0.28);
  backdrop-filter: blur(28px);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-6px);
  transition: opacity var(--transition-fast), transform var(--transition-fast), visibility var(--transition-fast);
}
.entity-select.is-open .entity-select__menu {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}
.entity-select__menu::-webkit-scrollbar {
  width: 6px;
}
.entity-select__menu::-webkit-scrollbar-track {
  background: transparent;
}
.entity-select__menu::-webkit-scrollbar-thumb {
  background: var(--text-muted);
  border-radius: 3px;
}
.entity-select__option {
  width: 100%;
  padding: 0.75rem 0.85rem;
  font: inherit;
  font-size: 0.9rem;
  color: var(--text-primary);
  background: transparent;
  border: 1px solid transparent;
  border-radius: 10px;
  text-align: left;
  cursor: pointer;
  transition: background var(--transition-fast), color var(--transition-fast), border-color var(--transition-fast);
}
.entity-select__option:hover,
.entity-select__option:focus-visible {
  background: var(--surface-hover);
  border-color: var(--surface-border);
  outline: none;
}
.entity-select__option[aria-selected="true"] {
  background: var(--selected-bg);
  color: var(--accent);
  box-shadow: 0 0 0 1px var(--selected-ring);
}

/* Details card */
.details-content {
  padding: var(--space-sm) 0;
}
.details__name {
  margin: 0 0 var(--space-md);
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-primary);
}
.details__meta {
  margin: 0;
  display: grid;
  grid-template-columns: auto 1fr;
  gap: var(--space-xs) var(--space-lg);
  font-size: 0.9rem;
}
.details__meta dt {
  margin: 0;
  color: var(--text-muted);
  font-weight: 500;
}
.details__meta dd {
  margin: 0;
  color: var(--text-primary);
  font-family: var(--font-mono);
}
.details__hint {
  margin: var(--space-md) 0 0;
  font-size: 0.85rem;
  color: var(--text-secondary);
  font-style: italic;
}

/* Fretboard flipped (left-handed) */
.fretboard-wrap.fretboard-wrap--left .fretboard__frets-nums,
.fretboard-wrap.fretboard-wrap--left .fretboard__grid,
.fretboard-wrap.fretboard-wrap--left .fretboard__positions {
  transform: scaleX(-1);
}
.fretboard-wrap.fretboard-wrap--left .fretboard__nut {
  left: auto;
  right: calc(var(--string-gutter) + ((100% - var(--string-gutter)) / var(--visible-frets)) - 3px);
}

@media (max-width: 700px) {
  .site-header {
    position: sticky;
    align-items: flex-start;
    flex-direction: column;
    gap: 0.65rem;
    padding: 0.75rem;
  }

  .brand-link img {
    height: clamp(3rem, 14vw, 3.6rem);
  }

  .mobile-nav-toggle {
    position: absolute;
    top: 1.25rem;
    right: 0.75rem;
    width: 2.7rem;
    height: 2.7rem;
    display: inline-flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 0.28rem;
    border-radius: 999px;
    color: #fff;
    background: rgba(255, 255, 255, 0.12);
    cursor: pointer;
    transition: background 180ms ease, transform 180ms ease;
  }

  .mobile-nav-toggle:hover,
  .mobile-nav-toggle:focus-visible {
    background: rgba(255, 255, 255, 0.2);
    outline: 0;
  }

  .mobile-nav-toggle span {
    width: 1.1rem;
    height: 2px;
    border-radius: 999px;
    background: currentColor;
    transition: transform 180ms ease, opacity 180ms ease;
  }

  .site-header.is-nav-open .mobile-nav-toggle span:nth-child(1) {
    transform: translateY(0.37rem) rotate(45deg);
  }

  .site-header.is-nav-open .mobile-nav-toggle span:nth-child(2) {
    opacity: 0;
  }

  .site-header.is-nav-open .mobile-nav-toggle span:nth-child(3) {
    transform: translateY(-0.37rem) rotate(-45deg);
  }

  .primary-nav {
    display: none;
    flex-direction: column;
    flex-wrap: nowrap;
    align-items: stretch;
    justify-content: flex-start;
    width: 100%;
    margin: 0;
    padding: 0.45rem;
    border: 1px solid rgba(255, 255, 255, 0.12);
    border-radius: 8px;
    background: rgba(3, 7, 18, 0.76);
    box-shadow: 0 18px 44px rgba(0, 0, 0, 0.28);
  }

  .primary-nav a {
    width: 100%;
    padding: 0.7rem 0.8rem;
    border-radius: 6px;
    font-size: 0.92rem;
  }

  .site-header.is-nav-open .primary-nav {
    display: flex;
  }

  .account-bar {
    width: 100%;
    display: none;
    flex-wrap: wrap;
    justify-content: space-between;
    gap: 0.55rem;
    min-width: 0;
    margin: -0.25rem 0 0;
    padding: 0.45rem;
    border: 1px solid rgba(255, 255, 255, 0.12);
    border-radius: 8px;
    background: rgba(3, 7, 18, 0.76);
    box-shadow: 0 18px 44px rgba(0, 0, 0, 0.28);
  }

  .site-header.is-nav-open .account-bar {
    display: flex;
  }

  .account-menu-wrap {
    max-width: 100%;
    min-width: 0;
  }

  .account-email {
    max-width: min(13rem, 54vw);
  }

  .account-menu-button {
    min-width: 0;
  }

  .account-menu {
    position: static;
    flex-basis: 100%;
    max-width: calc(100vw - 1.5rem);
    margin-top: 0.45rem;
  }

  .app {
    padding: 1rem 0.75rem 1.25rem;
    gap: 1rem;
  }

  .tool-header h1 {
    font-size: clamp(2rem, 12vw, 3rem);
  }

  .tool-header p {
    font-size: 0.95rem;
  }

  .card {
    padding: 1rem;
    border-radius: 10px;
  }

  .card--controls,
  .card--controls.is-open {
    padding: 0.9rem;
  }

  .card__title-toggle-content {
    align-items: flex-start;
    flex-direction: column;
    gap: 0.25rem;
  }

  .card__title-summary {
    max-width: calc(100vw - 5rem);
  }

  .controls-grid {
    grid-template-columns: 1fr;
    gap: 0.85rem;
  }

  .setting-select__trigger,
  .entity-select__trigger {
    min-height: 44px;
    font-size: 16px;
  }

  .setting-select__menu,
  .setting-select[data-setting="tuning"] .setting-select__menu,
  .entity-select__menu,
  .entity-select--wide .entity-select__menu {
    width: min(100%, calc(100vw - 2rem));
    max-width: none;
  }

  .card--fretboard {
    padding: 1rem 0.75rem 0.8rem;
  }

  .fretboard__status {
    justify-content: flex-start;
    gap: 0.45rem;
  }

  .instrument-toggle {
    width: 100%;
    display: grid;
    grid-template-columns: 1fr 1fr;
  }

  .instrument-toggle button {
    min-height: 2.4rem;
  }

  .fretboard__status-slot {
    flex: 1 1 calc(50% - 0.45rem);
  }

  .fretboard__status-slot--wide {
    flex-basis: 100%;
  }

  .fretboard__status-select,
  .fretboard__status-select .entity-select__trigger {
    width: 100%;
  }

  .fretboard-wrap,
  .keyboard-scroll {
    overflow-x: auto;
    overscroll-behavior-x: contain;
    -webkit-overflow-scrolling: touch;
  }

  .fretboard {
    min-width: 520px;
  }

  .keyboard {
    min-width: 920px;
    height: 13rem;
  }

  .piano-key--black {
    height: 7.85rem;
  }

  .details__meta {
    grid-template-columns: 1fr;
    gap: 0.2rem;
  }

  .details__meta dd {
    margin-bottom: 0.55rem;
    overflow-wrap: anywhere;
  }
}

@media (max-width: 620px) {
  .header__top {
    grid-template-columns: 1fr;
    gap: var(--space-md);
  }

  .header__nav-asset,
  .header__title {
    grid-column: 1;
    justify-self: center;
  }

  .header__logo {
    height: 4rem;
  }
}

@media (max-width: 430px) {
  .account-link,
  .account-button,
  .account-menu-link {
    font-size: 0.84rem;
  }

  .account-email {
    max-width: 48vw;
    font-size: 0.8rem;
  }

  .fretboard {
    min-width: 500px;
  }

  .note-marker {
    width: 25px;
    height: 25px;
    min-width: 25px;
    min-height: 25px;
    font-size: 0.64rem;
  }
}

@keyframes twinkle {
  0%,
  100% {
    opacity: 0.78;
  }

  50% {
    opacity: 0.16;
  }
}

@keyframes shoot {
  from {
    opacity: 1;
    translate: 0 0;
  }

  to {
    opacity: 0;
    translate: -800px 800px;
  }
}