@layer reset, tokens, base, components, layout, responsive, print;

@layer reset {
  *, *::before, *::after { box-sizing: border-box; }
  html { scroll-behavior: smooth; }
  body, h1, h2, h3, p, dl, dd, fieldset { margin: 0; }
  button, input, select, output { font: inherit; }
  button { color: inherit; }
  img, svg { display: block; max-width: 100%; }
  a { color: inherit; }
  [hidden] { display: none !important; }
}

@layer tokens {
  :root {
    --paper: #f5f0e6;
    --paper-raised: #fbf8f1;
    --paper-deep: #e9e1d3;
    --ink: #1d1d1a;
    --ink-soft: #5c5a52;
    --line: #c9c1b3;
    --line-strong: #817b70;
    --accent: #9a5528;
    --accent-deep: #713818;
    --accent-soft: #ead8c7;
    --success: #275f49;
    --success-soft: #dce9e1;
    --warning: #8a5b13;
    --warning-soft: #f2e7cb;
    --danger: #8a3532;
    --danger-soft: #eddad8;
    --focus: #195f86;
    --font-display: "Iowan Old Style", "Palatino Linotype", Palatino, Georgia, serif;
    --font-ui: ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    --font-code: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
    --content: 1480px;
    --reading: 760px;
    --header-height: 62px;
    --radius: 7px;
    --radius-large: 12px;
    --shadow-dialog: 0 20px 60px rgb(29 29 26 / 18%);
  }
}

@layer base {
  html {
    min-width: 320px;
    background: var(--paper);
    color: var(--ink);
    font-family: var(--font-ui);
    font-size: 16px;
    line-height: 1.55;
    text-rendering: optimizeLegibility;
    -webkit-text-size-adjust: 100%;
  }

  body {
    min-height: 100vh;
    overflow-x: hidden;
    background:
      linear-gradient(to right, transparent calc(50% - 0.5px), rgb(129 123 112 / 8%) 50%, transparent calc(50% + 0.5px)) top center / min(100% - 40px, var(--content)) 1px no-repeat,
      var(--paper);
  }

  h1, h2, h3 {
    font-family: var(--font-display);
    font-weight: 600;
    line-height: 1.03;
    text-wrap: balance;
  }

  h1 { font-size: clamp(2.4rem, 5vw, 4.6rem); letter-spacing: -0.045em; }
  h2 { font-size: clamp(2rem, 3.5vw, 3.25rem); letter-spacing: -0.035em; }
  h3 { font-size: clamp(1.35rem, 2vw, 1.8rem); letter-spacing: -0.02em; }

  p { text-wrap: pretty; }

  a:hover { color: var(--accent-deep); }

  button, select, input {
    border-radius: var(--radius);
  }

  button {
    border: 0;
    background: transparent;
    cursor: pointer;
  }

  button:disabled, select:disabled, input:disabled {
    cursor: not-allowed;
    opacity: 0.48;
  }

  :focus-visible {
    outline: 3px solid var(--focus);
    outline-offset: 3px;
  }

  ::selection {
    background: var(--accent-soft);
    color: var(--ink);
  }

  kbd {
    display: inline-flex;
    min-width: 1.7em;
    min-height: 1.7em;
    align-items: center;
    justify-content: center;
    border: 1px solid var(--line-strong);
    border-bottom-width: 2px;
    border-radius: 4px;
    background: var(--paper-raised);
    font-family: var(--font-code);
    font-size: 0.72rem;
    line-height: 1;
  }

  .clipboard-fallback {
    position: fixed;
    left: -9999px;
    width: 1px;
    height: 1px;
    opacity: 0;
  }

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

  .skip-link {
    position: fixed;
    z-index: 1000;
    top: 10px;
    left: 10px;
    transform: translateY(-160%);
    padding: 10px 14px;
    border: 2px solid var(--ink);
    border-radius: var(--radius);
    background: var(--paper-raised);
    font-weight: 750;
  }

  .skip-link:focus { transform: translateY(0); }

  .eyebrow {
    color: var(--accent-deep);
    font-family: var(--font-code);
    font-size: 0.72rem;
    font-weight: 750;
    letter-spacing: 0.09em;
    line-height: 1.3;
    text-transform: uppercase;
  }

  .control-label,
  label,
  legend {
    color: var(--ink-soft);
    font-size: 0.78rem;
    font-weight: 750;
    letter-spacing: 0.025em;
  }
}

@layer components {
  .button {
    min-height: 44px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 10px 16px;
    border: 1px solid transparent;
    font-size: 0.88rem;
    font-weight: 760;
    line-height: 1.1;
    text-decoration: none;
    transition: background-color 140ms ease-out, border-color 140ms ease-out, color 140ms ease-out, transform 140ms ease-out;
  }

  .button:active:not(:disabled) { transform: translateY(1px); }
  .button--compact { min-height: 38px; padding: 8px 12px; font-size: 0.78rem; }
  .button--accent { background: var(--accent); color: #fffaf1; }
  .button--accent:hover { background: var(--accent-deep); }
  .button--ink { background: var(--ink); color: var(--paper-raised); }
  .button--ink:hover { background: var(--accent-deep); }
  .button--outline { border-color: var(--line-strong); background: transparent; }
  .button--outline:hover { border-color: var(--ink); background: var(--paper-raised); }
  .button--text { min-height: 36px; padding-inline: 4px; color: var(--accent-deep); text-decoration: underline; text-decoration-thickness: 1px; text-underline-offset: 4px; }

  .icon-button {
    min-width: 42px;
    min-height: 38px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 7px;
    padding: 7px 10px;
    border: 1px solid var(--line);
    border-radius: var(--radius);
    font-size: 0.8rem;
    font-weight: 700;
  }

  .icon-button:hover { border-color: var(--line-strong); background: var(--paper-raised); }

  input[type="text"],
  input[type="search"],
  select {
    width: 100%;
    min-height: 44px;
    border: 1px solid var(--line-strong);
    background: var(--paper-raised);
    color: var(--ink);
    padding: 9px 12px;
  }

  select { padding-right: 34px; }

  input::placeholder { color: #77736b; }

  .input-with-button { display: flex; align-items: stretch; }
  .input-with-button input { border-radius: var(--radius) 0 0 var(--radius); }
  .input-with-button .button { border-radius: 0 var(--radius) var(--radius) 0; }

  .segmented-field {
    min-width: 0;
    padding: 0;
    border: 0;
  }

  .segmented-field legend { margin-bottom: 5px; }

  .segmented-control {
    display: inline-flex;
    min-height: 44px;
    border: 1px solid var(--line-strong);
    border-radius: var(--radius);
    background: var(--paper-raised);
    overflow: hidden;
  }

  .segmented-control button {
    min-width: 70px;
    padding: 8px 13px;
    border-right: 1px solid var(--line);
    border-radius: 0;
    font-size: 0.78rem;
    font-weight: 720;
  }

  .segmented-control button:last-child { border-right: 0; }
  .segmented-control button[aria-pressed="true"] { background: var(--ink); color: var(--paper-raised); }
  .segmented-control button:hover:not([aria-pressed="true"]) { background: var(--paper-deep); }

  .flute-diagram {
    width: 100%;
    height: auto;
    color: var(--ink);
    overflow: visible;
  }

  .flute-tube,
  .flute-rod,
  .mechanism-arm {
    fill: none;
    stroke: currentColor;
    stroke-linecap: round;
    stroke-linejoin: round;
    vector-effect: non-scaling-stroke;
  }

  .flute-tube { stroke-width: 15; opacity: 0.18; }
  .flute-rod { stroke-width: 3; opacity: 0.66; }
  .mechanism-arm { stroke-width: 3; opacity: 0.5; }
  .mechanism-arm--aux { stroke-width: 2; stroke-dasharray: 4 4; }
  .flute-crown { fill: var(--ink); opacity: 0.7; }
  .embouchure-hole { fill: var(--paper-raised); stroke: var(--ink); stroke-width: 4; vector-effect: non-scaling-stroke; }

  .key-shape {
    fill: var(--paper-raised);
    stroke: var(--ink);
    stroke-width: 3;
    vector-effect: non-scaling-stroke;
    transition: fill 140ms ease-out, stroke 140ms ease-out, opacity 140ms ease-out;
  }

  .key-shape--side,
  .key-shape--foot { stroke-width: 2.5; }

  .flute-key--pressed .key-shape { fill: var(--accent); stroke: var(--accent-deep); }
  .flute-key--unchanged .key-shape { fill: var(--ink); stroke: var(--ink); }
  .flute-key--added .key-shape { fill: var(--success); stroke: var(--success); }
  .flute-key--released .key-shape { fill: var(--paper-raised); stroke: var(--danger); stroke-width: 4; stroke-dasharray: 6 4; }
  .key-center-mark { fill: var(--paper-raised); pointer-events: none; }
  .key-status-mark { fill: var(--paper-raised); font-family: var(--font-ui); font-size: 22px; font-weight: 900; pointer-events: none; }
  .flute-key--released .key-status-mark { fill: var(--danger); }

  .key-label {
    fill: var(--ink-soft);
    font-family: var(--font-code);
    font-size: 15px;
    font-weight: 700;
    pointer-events: none;
  }

  .flute-diagram--vertical .key-label { font-size: 14px; }
  .flute-diagram--compact .key-label { display: none; }
  .flute-diagram--compact .flute-tube { stroke-width: 10; }
  .flute-diagram--compact .flute-rod { stroke-width: 2; }

  .flute-diagram--editable .flute-key { cursor: pointer; }
  .flute-diagram--editable .flute-key:hover .key-shape { stroke: var(--focus); stroke-width: 4; }
  .flute-diagram--editable .flute-key:focus-visible { outline: none; }
  .flute-diagram--editable .flute-key:focus-visible .key-shape { stroke: var(--focus); stroke-width: 6; }

  .music-staff { width: min(100%, 250px); height: auto; }
  .staff-line, .staff-ledger, .staff-stem { stroke: var(--ink); stroke-width: 2; vector-effect: non-scaling-stroke; }
  .staff-notehead { fill: var(--ink); }
  .treble-clef { fill: var(--ink); font-family: Georgia, serif; font-size: 72px; }
  .staff-accidental { fill: var(--ink); font-family: Georgia, serif; font-size: 34px; }
  .music-staff--compact .treble-clef { opacity: 0.72; }

  .legend-key {
    width: 18px;
    height: 18px;
    display: inline-block;
    flex: 0 0 18px;
    border: 2px solid var(--ink);
    border-radius: 50%;
    background: var(--paper-raised);
  }

  .legend-key--pressed { background: var(--accent); border-color: var(--accent-deep); }
  .legend-key--open { background: var(--paper-raised); }
  .legend-key--unchanged { background: var(--ink); }
  .legend-key--added { background: var(--success); border-color: var(--success); }
  .legend-key--released { border: 3px dashed var(--danger); }

  .inline-notice {
    padding: 10px 12px;
    border-left: 3px solid var(--warning);
    background: var(--warning-soft);
    color: #5c3a05;
    font-size: 0.83rem;
  }

  .text-link {
    padding: 0;
    color: var(--accent-deep);
    font-weight: 750;
    text-decoration: underline;
    text-underline-offset: 4px;
  }

  .toast {
    position: fixed;
    z-index: 100;
    right: 20px;
    bottom: 20px;
    max-width: min(360px, calc(100vw - 40px));
    padding: 12px 16px;
    border: 1px solid var(--ink);
    border-radius: var(--radius);
    background: var(--ink);
    color: var(--paper-raised);
    box-shadow: 0 8px 28px rgb(29 29 26 / 18%);
    font-size: 0.86rem;
    font-weight: 680;
  }
}

@layer layout {
  .site-header {
    position: sticky;
    z-index: 50;
    top: 0;
    width: 100%;
    min-height: var(--header-height);
    display: grid;
    grid-template-columns: minmax(240px, 0.8fr) minmax(420px, 1.4fr) minmax(250px, 0.8fr);
    align-items: center;
    gap: 20px;
    padding: 8px max(20px, calc((100vw - var(--content)) / 2));
    border-bottom: 1px solid var(--line);
    background: rgb(245 240 230 / 94%);
    backdrop-filter: blur(14px);
  }

  .brand {
    display: inline-flex;
    width: fit-content;
    align-items: center;
    gap: 11px;
    color: var(--ink);
    text-decoration: none;
  }

  .brand:hover { color: var(--ink); }
  .brand-mark { color: var(--accent); font-family: var(--font-code); font-size: 0.82rem; letter-spacing: -0.11em; transform: rotate(-18deg); }
  .brand-copy { display: grid; line-height: 1.05; }
  .brand-copy strong { font-family: var(--font-display); font-size: 1rem; }
  .brand-copy small { margin-top: 3px; color: var(--ink-soft); font-family: var(--font-code); font-size: 0.61rem; letter-spacing: 0.06em; text-transform: uppercase; }

  .mode-nav {
    display: flex;
    justify-content: center;
    gap: 3px;
  }

  .mode-nav__button {
    min-height: 38px;
    padding: 7px 11px;
    border-radius: 4px;
    color: var(--ink-soft);
    font-size: 0.76rem;
    font-weight: 760;
  }

  .mode-nav__button:hover { background: var(--paper-deep); color: var(--ink); }
  .mode-nav__button.is-active { background: var(--ink); color: var(--paper-raised); }

  .header-actions { display: flex; justify-content: flex-end; align-items: center; gap: 8px; }

  main { min-height: 70vh; }

  .workspace {
    width: min(calc(100% - 40px), var(--content));
    min-height: calc(100vh - var(--header-height));
    margin: 0 auto;
    padding: 30px 0 48px;
  }

  .workspace-heading {
    display: grid;
    grid-template-columns: minmax(0, 1fr) minmax(280px, 520px);
    align-items: end;
    gap: 40px;
    margin-bottom: 24px;
  }

  .workspace-heading h1,
  .workspace-heading h2 { margin-top: 5px; }
  .workspace-heading__summary { max-width: 520px; color: var(--ink-soft); font-size: 0.94rem; }

  .finder-toolbar {
    display: grid;
    grid-template-columns: minmax(270px, 1fr) auto auto;
    align-items: end;
    gap: 18px;
    padding: 15px 0;
    border-top: 1px solid var(--line);
    border-bottom: 1px solid var(--line);
  }

  .note-search label { display: block; margin-bottom: 5px; }

  .note-rail-shell {
    display: grid;
    grid-template-columns: 38px minmax(0, 1fr) 38px;
    align-items: center;
    gap: 6px;
    padding: 14px 0;
  }

  .rail-arrow,
  .note-stepper button,
  .scale-actions > button:not(.button),
  .swap-button {
    min-width: 38px;
    min-height: 38px;
    border: 1px solid var(--line);
    border-radius: var(--radius);
    background: var(--paper-raised);
    font-size: 1.25rem;
    line-height: 1;
  }

  .rail-arrow:hover,
  .note-stepper button:hover,
  .scale-actions > button:not(.button):hover,
  .swap-button:hover { border-color: var(--ink); }

  .note-rail {
    display: flex;
    gap: 5px;
    overflow-x: auto;
    overscroll-behavior-x: contain;
    scroll-behavior: smooth;
    scroll-snap-type: x proximity;
    scrollbar-width: thin;
    scrollbar-color: var(--line-strong) transparent;
    padding: 2px;
  }

  .note-rail::before,
  .note-rail::after { content: ""; flex: 0 0 1px; }

  .note-rail__group {
    flex: 0 0 auto;
    display: flex;
    align-items: center;
    gap: 5px;
    padding-right: 11px;
    margin-right: 6px;
    border-right: 1px solid var(--line);
  }

  .note-rail__group:last-child { padding-right: 0; margin-right: 0; border-right: 0; }
  .note-rail__label { align-self: stretch; display: grid; place-items: center; writing-mode: vertical-rl; transform: rotate(180deg); color: var(--ink-soft); font-family: var(--font-code); font-size: 0.58rem; letter-spacing: 0.05em; text-transform: uppercase; }

  .note-chip {
    min-width: 49px;
    min-height: 44px;
    flex: 0 0 auto;
    scroll-snap-align: center;
    border: 1px solid transparent;
    border-radius: 5px;
    font-family: var(--font-code);
    font-size: 0.75rem;
    font-weight: 720;
  }

  .note-chip:hover:not(:disabled) { border-color: var(--line-strong); background: var(--paper-raised); }
  .note-chip[aria-selected="true"] { border-color: var(--ink); background: var(--ink); color: var(--paper-raised); box-shadow: inset 0 -4px 0 var(--accent); }
  .note-chip:disabled { text-decoration: line-through; }

  .finder-stage {
    min-height: 440px;
    display: grid;
    grid-template-columns: minmax(320px, 0.86fr) minmax(0, 1.6fr);
    border-top: 1px solid var(--line-strong);
    border-bottom: 1px solid var(--line-strong);
  }

  .note-result {
    min-width: 0;
    padding: 24px 30px 24px 0;
    border-right: 1px solid var(--line);
  }

  .note-result__heading { display: flex; align-items: flex-start; justify-content: space-between; gap: 16px; }
  .note-result__heading h2 { margin-top: -3px; font-size: clamp(4.7rem, 8vw, 7.5rem); letter-spacing: -0.075em; line-height: 0.84; }

  .tone-button {
    min-width: 112px;
    min-height: 46px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 9px 12px;
    border: 1px solid var(--line-strong);
    border-radius: var(--radius);
    background: var(--paper-raised);
    font-size: 0.72rem;
    font-weight: 760;
  }

  .tone-button:hover { border-color: var(--accent); color: var(--accent-deep); }
  .tone-button.is-playing span:first-child { animation: pulse 700ms ease-in-out infinite alternate; }

  .selected-staff { width: 220px; margin: 5px 0 -8px; }

  .note-facts {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 10px;
    padding: 12px 0;
    border-top: 1px solid var(--line);
    border-bottom: 1px solid var(--line);
  }

  .note-facts div { min-width: 0; }
  .note-facts dt { color: var(--ink-soft); font-size: 0.64rem; font-weight: 750; letter-spacing: 0.06em; text-transform: uppercase; }
  .note-facts dd { overflow: hidden; margin-top: 2px; font-family: var(--font-code); font-size: 0.73rem; text-overflow: ellipsis; white-space: nowrap; }

  .variant-block { padding: 13px 0 10px; }
  .variant-block__heading { display: flex; align-items: center; justify-content: space-between; margin-bottom: 7px; }
  .variant-count { color: var(--ink-soft); font-family: var(--font-code); font-size: 0.66rem; }
  .variant-tabs { display: flex; flex-wrap: wrap; gap: 5px; }

  .variant-tab {
    min-height: 34px;
    padding: 6px 10px;
    border: 1px solid var(--line);
    border-radius: 4px;
    font-size: 0.7rem;
    font-weight: 720;
  }

  .variant-tab[aria-selected="true"] { border-color: var(--ink); background: var(--ink); color: var(--paper-raised); }
  .variant-use { margin-top: 7px; color: var(--ink-soft); font-size: 0.76rem; }

  .fingering-instruction { padding: 12px 14px; border-left: 3px solid var(--accent); background: var(--paper-raised); }
  .fingering-code { font-family: var(--font-code); font-size: 0.86rem; font-weight: 800; letter-spacing: 0.015em; }
  .fingering-instruction p:last-child { margin-top: 6px; color: var(--ink-soft); font-size: 0.78rem; }
  .result-actions { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; margin-top: 13px; }

  .diagram-panel { min-width: 0; padding: 24px 0 20px 30px; }
  .diagram-panel__heading { display: flex; align-items: flex-start; justify-content: space-between; gap: 20px; }
  .diagram-panel__heading h2 { margin-top: 5px; font-size: clamp(1.45rem, 2.5vw, 2.05rem); }
  .note-stepper { display: flex; align-items: center; gap: 8px; }
  .note-stepper span { min-width: 62px; color: var(--ink-soft); font-family: var(--font-code); font-size: 0.68rem; text-align: center; }

  .main-diagram {
    width: 100%;
    min-height: 300px;
    display: grid;
    align-items: center;
    padding: 3px 0;
  }

  .main-diagram .flute-diagram--horizontal { max-height: 330px; }
  .main-diagram .flute-diagram--vertical { max-height: 570px; }

  .diagram-legend { display: flex; flex-wrap: wrap; align-items: center; gap: 12px 18px; padding-top: 10px; border-top: 1px solid var(--line); color: var(--ink-soft); font-size: 0.68rem; }
  .diagram-legend span { display: inline-flex; align-items: center; gap: 6px; }
  .diagram-caption { margin-top: 7px; color: var(--ink-soft); font-size: 0.7rem; }

  .compare-controls,
  .scale-toolbar,
  .quiz-toolbar,
  .chart-toolbar {
    display: grid;
    align-items: end;
    gap: 14px;
    padding: 16px 0;
    border-top: 1px solid var(--line);
    border-bottom: 1px solid var(--line);
  }

  .compare-controls { grid-template-columns: minmax(180px, 1fr) 44px minmax(180px, 1fr) auto; }
  .compare-controls label,
  .scale-toolbar label,
  .quiz-toolbar > label,
  .chart-toolbar label { display: grid; gap: 5px; }
  .swap-button { align-self: end; min-height: 44px; }

  .compare-stage {
    min-height: 470px;
    display: grid;
    grid-template-columns: minmax(280px, 0.65fr) minmax(0, 1.35fr);
    align-items: center;
    gap: 40px;
    padding: 30px 0;
    border-bottom: 1px solid var(--line-strong);
  }

  .compare-copy h3 { margin-top: 7px; font-size: clamp(2rem, 4vw, 3.7rem); }
  .transition-list { margin: 24px 0; border-top: 1px solid var(--line); }
  .transition-list > div { display: grid; grid-template-columns: 150px 1fr; gap: 12px; padding: 11px 0; border-bottom: 1px solid var(--line); }
  .transition-list dt { display: flex; align-items: center; gap: 8px; color: var(--ink-soft); font-size: 0.74rem; font-weight: 750; }
  .transition-list dd { font-family: var(--font-code); font-size: 0.76rem; }
  .compare-diagram { min-width: 0; }
  .compare-diagram.is-animating .flute-key .key-shape { transition-duration: 360ms; }

  .scale-toolbar { grid-template-columns: minmax(180px, 0.6fr) minmax(250px, 1fr) auto; }
  .range-field { min-height: 44px; display: grid; grid-template-columns: 1fr 70px; align-items: center; gap: 10px; }
  .range-field input { width: 100%; accent-color: var(--accent); }
  .range-field output { color: var(--ink); font-family: var(--font-code); font-size: 0.72rem; }
  .scale-actions { display: flex; align-items: center; gap: 7px; }

  .scale-steps { display: grid; grid-template-columns: repeat(8, minmax(66px, 1fr)); border-bottom: 1px solid var(--line); }
  .scale-step { min-height: 58px; padding: 8px 6px; border-right: 1px solid var(--line); border-radius: 0; text-align: center; }
  .scale-step:last-child { border-right: 0; }
  .scale-step small { display: block; color: var(--ink-soft); font-family: var(--font-code); font-size: 0.58rem; }
  .scale-step strong { display: block; margin-top: 2px; font-family: var(--font-display); font-size: 1.2rem; }
  .scale-step[aria-current="step"] { background: var(--ink); color: var(--paper-raised); }
  .scale-step[aria-current="step"] small { color: var(--paper-deep); }

  .practice-stage {
    min-height: 460px;
    display: grid;
    grid-template-columns: minmax(230px, 0.45fr) minmax(0, 1.55fr);
    align-items: center;
    gap: 35px;
    padding: 24px 0;
    border-bottom: 1px solid var(--line-strong);
  }

  .practice-note { padding-right: 25px; border-right: 1px solid var(--line); }
  .practice-note h3 { margin-top: 4px; font-size: clamp(4rem, 8vw, 7rem); letter-spacing: -0.07em; }
  .practice-note .music-staff { width: 190px; margin-block: -5px; }
  .practice-diagram .flute-diagram { max-height: 350px; }

  .quiz-toolbar { grid-template-columns: auto minmax(210px, 0.7fr) minmax(260px, 1fr); }
  .quiz-stats { display: grid; grid-template-columns: repeat(3, 1fr); border: 1px solid var(--line); border-radius: var(--radius); background: var(--paper-raised); }
  .quiz-stats div { padding: 7px 12px; border-right: 1px solid var(--line); text-align: center; }
  .quiz-stats div:last-child { border-right: 0; }
  .quiz-stats dt { color: var(--ink-soft); font-size: 0.58rem; font-weight: 750; letter-spacing: 0.06em; text-transform: uppercase; }
  .quiz-stats dd { font-family: var(--font-code); font-size: 0.86rem; font-weight: 750; }

  .quiz-stage {
    min-height: 410px;
    display: grid;
    grid-template-columns: minmax(240px, 0.5fr) minmax(0, 1.5fr);
    align-items: center;
    gap: 35px;
    padding: 24px 0;
  }

  .quiz-prompt h3 { margin-top: 8px; font-size: clamp(2.3rem, 5vw, 4.6rem); }
  .quiz-prompt > p:last-child { max-width: 330px; margin-top: 12px; color: var(--ink-soft); font-size: 0.86rem; }
  .quiz-prompt .music-staff { margin-top: 5px; }
  .quiz-diagram .flute-diagram { max-height: 390px; }
  .quiz-choices { display: grid; grid-template-columns: repeat(4, 1fr); gap: 10px; max-width: 920px; margin: 0 auto; }
  .quiz-choice { min-height: 62px; border: 1px solid var(--line-strong); background: var(--paper-raised); font-family: var(--font-display); font-size: 1.3rem; font-weight: 650; }
  .quiz-choice:hover:not(:disabled) { border-color: var(--accent); }
  .quiz-choice.is-correct { border-color: var(--success); background: var(--success-soft); color: #123f2e; }
  .quiz-choice.is-incorrect { border-color: var(--danger); background: var(--danger-soft); color: #5e1d1b; }
  .quiz-build-actions { display: flex; justify-content: center; gap: 14px; }
  .quiz-feedback { min-height: 28px; margin-top: 16px; text-align: center; font-weight: 740; }
  .quiz-feedback.is-correct { color: var(--success); }
  .quiz-feedback.is-incorrect { color: var(--danger); }
  .quiz-next { display: flex; margin: 10px auto 0; }

  .chart-toolbar { grid-template-columns: minmax(240px, 1fr) minmax(180px, 0.5fr) auto; }
  .chart-count { padding: 12px 0; color: var(--ink-soft); font-family: var(--font-code); font-size: 0.72rem; }
  .chart-grid { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); border-top: 1px solid var(--line-strong); border-left: 1px solid var(--line); }
  .chart-card { min-width: 0; padding: 14px; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); background: rgb(251 248 241 / 46%); }
  .chart-card__heading { display: flex; align-items: baseline; justify-content: space-between; gap: 10px; }
  .chart-card__heading h3 { font-size: 1.55rem; }
  .chart-card__heading small { color: var(--ink-soft); font-family: var(--font-code); font-size: 0.6rem; text-transform: uppercase; }
  .chart-card__diagram { min-height: 100px; display: grid; align-items: center; margin-block: 7px; }
  .chart-card .fingering-code { overflow-wrap: anywhere; font-size: 0.68rem; }
  .chart-card__action { margin-top: 8px; padding: 0; color: var(--accent-deep); font-size: 0.7rem; font-weight: 750; text-decoration: underline; text-underline-offset: 3px; }
  .chart-empty { grid-column: 1 / -1; padding: 40px 20px; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); color: var(--ink-soft); text-align: center; }

  .learning,
  .methodology,
  .site-footer {
    width: min(calc(100% - 40px), var(--content));
    margin-inline: auto;
  }

  .learning { padding: 90px 0 70px; }
  .learning-intro { display: grid; grid-template-columns: minmax(260px, 0.75fr) minmax(320px, 1.25fr); gap: 80px; align-items: end; padding-bottom: 40px; border-bottom: 1px solid var(--line-strong); }
  .learning-intro h2 { margin-top: 7px; }
  .learning-intro > p:last-child { max-width: 680px; color: var(--ink-soft); font-size: 1.05rem; }
  .learning-grid { display: grid; grid-template-columns: repeat(4, 1fr); border-left: 1px solid var(--line); }
  .learning-grid article { min-width: 0; padding: 28px 25px 30px; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); }
  .section-number { color: var(--accent); font-family: var(--font-code); font-size: 0.7rem; }
  .learning-grid h3 { margin: 22px 0 13px; font-size: 1.5rem; }
  .learning-grid p { color: var(--ink-soft); font-size: 0.86rem; }
  .inline-note-links { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 18px; }
  .inline-note-links button { min-width: 44px; min-height: 38px; padding: 6px 10px; border: 1px solid var(--line-strong); background: var(--paper-raised); font-family: var(--font-code); font-size: 0.72rem; font-weight: 740; }
  .inline-note-links button:hover { border-color: var(--accent); }
  .learning-grid .text-link { margin-top: 18px; font-size: 0.75rem; text-align: left; }

  .methodology { display: grid; grid-template-columns: minmax(260px, 0.65fr) minmax(0, 1.35fr); gap: 80px; padding: 65px 0; border-top: 1px solid var(--line-strong); }
  .methodology h2 { margin-top: 7px; }
  .methodology-copy { max-width: 820px; }
  .methodology-copy p + p { margin-top: 18px; }
  .methodology-copy p { color: var(--ink-soft); }
  .methodology-copy a { color: var(--accent-deep); text-decoration-thickness: 1px; text-underline-offset: 3px; }
  .review-note { font-family: var(--font-code); font-size: 0.72rem; }

  .site-footer {
    display: flex;
    align-items: flex-end;
    justify-content: space-between;
    gap: 30px;
    padding: 35px 0 50px;
    border-top: 1px solid var(--line-strong);
  }

  .site-footer strong { font-family: var(--font-display); font-size: 1.1rem; }
  .site-footer p { margin-top: 3px; color: var(--ink-soft); font-size: 0.76rem; }
  .footer-links { display: flex; flex-wrap: wrap; justify-content: flex-end; gap: 18px; }
  .footer-links a, .footer-links button { padding: 0; color: var(--ink-soft); font-size: 0.76rem; text-decoration: underline; text-underline-offset: 4px; }

  .site-dialog {
    width: min(560px, calc(100vw - 28px));
    max-height: min(760px, calc(100vh - 28px));
    padding: 0;
    border: 1px solid var(--ink);
    border-radius: var(--radius-large);
    background: var(--paper-raised);
    color: var(--ink);
    box-shadow: var(--shadow-dialog);
  }

  .site-dialog--wide { width: min(820px, calc(100vw - 28px)); }
  .site-dialog::backdrop { background: rgb(29 29 26 / 56%); backdrop-filter: blur(3px); }
  .dialog-shell { padding: 25px; }
  .dialog-heading { display: flex; align-items: flex-start; justify-content: space-between; gap: 24px; padding-bottom: 17px; border-bottom: 1px solid var(--line); }
  .dialog-heading h2 { margin-top: 5px; font-size: 2rem; }
  .dialog-close { width: 42px; height: 42px; border: 1px solid var(--line); border-radius: 50%; font-size: 1.7rem; line-height: 1; }
  .dialog-close:hover { border-color: var(--ink); }
  .dialog-fieldset { display: grid; grid-template-columns: 1fr 1fr; gap: 8px 18px; padding: 18px 0; border: 0; border-bottom: 1px solid var(--line); }
  .dialog-fieldset legend { grid-column: 1 / -1; margin-bottom: 7px; color: var(--ink); }
  .dialog-fieldset label { display: flex; align-items: center; gap: 8px; color: var(--ink); font-size: 0.86rem; font-weight: 550; }
  .dialog-fieldset input { accent-color: var(--accent); }
  .shortcut-list { padding: 18px 0; }
  .shortcut-list h3 { font-family: var(--font-ui); font-size: 0.82rem; }
  .shortcut-list dl { margin-top: 10px; }
  .shortcut-list dl > div { display: grid; grid-template-columns: 110px 1fr; gap: 10px; padding: 7px 0; border-bottom: 1px solid var(--line); }
  .shortcut-list dt { display: flex; gap: 5px; }
  .shortcut-list dd { color: var(--ink-soft); font-size: 0.78rem; }
  .legal-copy { overflow: auto; max-height: calc(100vh - 170px); padding-top: 20px; }
  .legal-copy section + section { margin-top: 27px; }
  .legal-copy h3 { font-size: 1.35rem; }
  .legal-copy p { margin-top: 8px; color: var(--ink-soft); font-size: 0.88rem; }
  .legal-copy .review-note { margin-top: 25px; }

  .noscript-message { max-width: var(--reading); margin: 30px auto; padding: 25px; border: 2px solid var(--warning); background: var(--warning-soft); }
  .noscript-message h2 { font-size: 1.5rem; }
  .noscript-message p { margin-top: 8px; }

  .error-page { min-height: 100vh; display: grid; place-items: center; padding: 24px; }
  .error-page__main { width: min(100%, 720px); padding: clamp(28px, 7vw, 70px); border-top: 1px solid var(--line-strong); border-bottom: 1px solid var(--line-strong); }
  .error-page__main h1 { margin-top: 10px; font-size: clamp(3rem, 9vw, 6rem); }
  .error-page__main > p:not(.eyebrow) { max-width: 580px; margin-top: 18px; color: var(--ink-soft); }
  .error-page__main .button { margin-top: 26px; }

  @keyframes pulse {
    from { opacity: 0.45; transform: scale(0.9); }
    to { opacity: 1; transform: scale(1.08); }
  }
}

@layer responsive {
  @media (max-width: 1180px) {
    .site-header { grid-template-columns: minmax(210px, 1fr) auto; }
    .mode-nav { grid-row: 2; grid-column: 1 / -1; justify-content: flex-start; overflow-x: auto; padding-top: 4px; border-top: 1px solid var(--line); }
    .header-actions { grid-column: 2; }
    .workspace { min-height: auto; }
    .finder-stage { grid-template-columns: minmax(300px, 0.75fr) minmax(0, 1.25fr); }
    .note-result { padding-right: 22px; }
    .diagram-panel { padding-left: 22px; }
    .chart-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
    .learning-grid { grid-template-columns: repeat(2, 1fr); }
  }

  @media (max-width: 860px) {
    :root { --header-height: 58px; }
    .site-header { position: sticky; grid-template-columns: 1fr auto; gap: 9px; padding-inline: 14px; }
    .brand-copy small { display: none; }
    .button-label { display: none; }
    .mode-nav { gap: 2px; }
    .mode-nav__button { flex: 0 0 auto; }
    .workspace { width: min(calc(100% - 28px), var(--content)); padding-top: 22px; }
    .workspace-heading { grid-template-columns: 1fr; gap: 10px; }
    .workspace-heading__summary { max-width: 680px; }
    .finder-toolbar { grid-template-columns: 1fr 1fr; }
    .note-search { grid-column: 1 / -1; }
    .finder-stage { grid-template-columns: 1fr; border-top: 1px solid var(--line-strong); }
    .note-result { padding: 22px 0; border-right: 0; border-bottom: 1px solid var(--line); }
    .diagram-panel { padding: 22px 0; }
    .main-diagram { min-height: 390px; }
    .main-diagram .flute-diagram--vertical { max-height: 560px; }
    .compare-stage, .practice-stage, .quiz-stage { grid-template-columns: 1fr; gap: 20px; }
    .compare-stage { align-items: start; }
    .practice-note { display: grid; grid-template-columns: auto 1fr; align-items: center; gap: 5px 25px; padding-right: 0; border-right: 0; border-bottom: 1px solid var(--line); }
    .practice-note .eyebrow, .practice-note .fingering-code { grid-column: 1 / -1; }
    .scale-toolbar { grid-template-columns: 1fr 1fr; }
    .scale-actions { grid-column: 1 / -1; }
    .quiz-toolbar { grid-template-columns: 1fr 1fr; }
    .quiz-stats { grid-column: 1 / -1; }
    .chart-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
    .learning-intro, .methodology { grid-template-columns: 1fr; gap: 25px; }
  }

  @media (max-width: 640px) {
    :root { --header-height: 54px; }
    html { font-size: 15px; }
    body { background: var(--paper); }
    .site-header { min-height: 54px; padding-top: 7px; padding-bottom: 0; }
    .brand-mark { display: none; }
    .brand-copy strong { font-size: 0.92rem; }
    .header-actions .button--ink { display: none; }
    .mode-nav { margin-inline: -14px; padding: 5px 14px 6px; scrollbar-width: none; }
    .mode-nav::-webkit-scrollbar { display: none; }
    .mode-nav__button { min-height: 34px; padding: 6px 10px; }

    .workspace { width: min(calc(100% - 22px), var(--content)); padding: 18px 0 34px; }
    .workspace-heading { margin-bottom: 17px; }
    .workspace-heading h1 { font-size: 2.75rem; }
    .workspace-heading h2 { font-size: 2.35rem; }
    .workspace-heading__summary { font-size: 0.82rem; }

    .finder-toolbar { grid-template-columns: 1fr 1fr; gap: 10px; padding: 11px 0; }
    .segmented-control { width: 100%; }
    .segmented-control button { min-width: 0; flex: 1; padding-inline: 8px; }
    .note-rail-shell { grid-template-columns: 32px minmax(0, 1fr) 32px; gap: 3px; padding: 9px 0; }
    .rail-arrow { min-width: 32px; min-height: 40px; }
    .note-chip { min-width: 47px; min-height: 42px; }

    .note-result { padding: 16px 0 18px; }
    .note-result__heading h2 { font-size: 5.4rem; }
    .tone-button { min-width: 96px; padding-inline: 8px; }
    .tone-button span:last-child { max-width: 62px; text-align: center; }
    .selected-staff { width: 175px; margin-top: -4px; }
    .note-facts { gap: 6px; }
    .note-facts dd { font-size: 0.65rem; }
    .result-actions { align-items: stretch; }
    .result-actions .button { flex: 1 1 150px; }

    .diagram-panel { padding: 18px 0; }
    .diagram-panel__heading h2 { font-size: 1.55rem; }
    .note-stepper span { display: none; }
    .main-diagram { min-height: 440px; }
    .main-diagram .flute-diagram--vertical { max-height: 520px; }
    .diagram-legend span:nth-child(n + 3) { display: none; }

    .compare-controls { grid-template-columns: 1fr 44px 1fr; }
    .compare-controls .button { grid-column: 1 / -1; }
    .compare-stage { min-height: 0; padding-top: 22px; }
    .transition-list > div { grid-template-columns: 125px 1fr; }

    .scale-toolbar, .quiz-toolbar, .chart-toolbar { grid-template-columns: 1fr; }
    .scale-actions, .quiz-stats { grid-column: auto; }
    .scale-actions { flex-wrap: wrap; }
    .scale-actions .button--accent { flex: 1; }
    .scale-steps { grid-template-columns: repeat(4, 1fr); }
    .scale-step:nth-child(4) { border-right: 0; }
    .scale-step:nth-child(-n + 4) { border-bottom: 1px solid var(--line); }
    .practice-note { grid-template-columns: auto 1fr; }
    .practice-note h3 { font-size: 4.5rem; }
    .practice-note .music-staff { width: 150px; }
    .quiz-stage { min-height: 0; }
    .quiz-choices { grid-template-columns: repeat(2, 1fr); }
    .quiz-build-actions { flex-wrap: wrap; }
    .chart-toolbar .button { width: 100%; }
    .chart-grid { grid-template-columns: 1fr; }

    .learning { width: min(calc(100% - 22px), var(--content)); padding: 65px 0 50px; }
    .learning-grid { grid-template-columns: 1fr; }
    .learning-grid article { padding: 24px 18px; }
    .methodology { width: min(calc(100% - 22px), var(--content)); padding: 45px 0; }
    .site-footer { width: min(calc(100% - 22px), var(--content)); align-items: flex-start; flex-direction: column; }
    .footer-links { justify-content: flex-start; }
    .dialog-shell { padding: 18px; }
    .dialog-fieldset { grid-template-columns: 1fr; }
    .toast { right: 11px; bottom: 11px; max-width: calc(100vw - 22px); }
  }

  @media (max-width: 390px) {
    .note-result__heading h2 { font-size: 4.7rem; }
    .tone-button { min-width: 84px; font-size: 0.66rem; }
    .input-with-button .button { padding-inline: 11px; }
    .main-diagram { min-height: 405px; }
  }

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

  @media (forced-colors: active) {
    .key-shape, .legend-key { forced-color-adjust: auto; }
    .flute-key--pressed .key-shape,
    .flute-key--added .key-shape,
    .flute-key--unchanged .key-shape { fill: CanvasText; }
    .note-chip[aria-selected="true"],
    .mode-nav__button.is-active,
    .segmented-control button[aria-pressed="true"] { border: 2px solid Highlight; background: Highlight; color: HighlightText; }
  }
}

@layer print {
  @page { size: auto; margin: 10mm; }

  @media print {
    :root { --paper: #fff; --paper-raised: #fff; --ink: #000; --ink-soft: #222; --line: #999; --line-strong: #333; }
    html, body { background: #fff !important; color: #000; font-size: 9pt; }
    body { overflow: visible; }
    .site-header,
    .learning,
    .methodology,
    .site-footer,
    .site-dialog,
    .toast,
    .noscript-message,
    [data-workspace]:not(#chart),
    #chart .workspace-heading__summary,
    .chart-toolbar,
    .chart-count,
    .chart-card__action { display: none !important; }

    #chart,
    #chart[hidden] {
      width: 100% !important;
      min-height: 0 !important;
      display: block !important;
      margin: 0 !important;
      padding: 0 !important;
    }

    #chart .workspace-heading {
      display: block;
      margin: 0 0 5mm;
      padding-bottom: 3mm;
      border-bottom: 1px solid #000;
    }

    #chart .workspace-heading::after {
      content: "Modern closed-G♯ Boehm concert flute · B3–C7 · A4 = 440 Hz · flutefingeringchart.org";
      display: block;
      margin-top: 2mm;
      font: 7.5pt/1.3 var(--font-code);
    }

    #chart h2 { font-size: 22pt; }
    #chart .eyebrow { color: #000; font-size: 7pt; }
    .chart-grid { grid-template-columns: repeat(4, 1fr) !important; border-color: #555; }
    .chart-card { min-height: 43mm; padding: 2.5mm; break-inside: avoid; background: #fff; border-color: #777; }
    .chart-card__heading h3 { font-size: 14pt; }
    .chart-card__heading small { color: #222; font-size: 6pt; }
    .chart-card__diagram { min-height: 20mm; margin: 1mm 0; }
    .chart-card .fingering-code { font-size: 6.3pt; }
    .flute-tube { opacity: 0.24; }
    .flute-key--pressed .key-shape,
    .flute-key--unchanged .key-shape,
    .flute-key--added .key-shape { fill: #000; stroke: #000; }
    .key-center-mark { fill: #fff; }
    .key-label { fill: #000; }
  }
}