:root {
  --font-base: 16pt;
  --font-medium: 22pt;
  --font-large: 28pt;
  --ink: #151718;
  --muted: #60615b;
  --paper: #f1eadc;
  --surface: #fffaf0;
  --line: #d6cbb8;
  --fretboard: #3d352f;
  --fretboard-dark: #252322;
  --fret: #c8b27f;
  --string: #e1e5e2;
  --root: #ffcf4a;
  --root-ink: #211805;
  --note: #78d3e7;
  --note-ink: #071d24;
  --focus: #2c6ee8;
}

* {
  box-sizing: border-box;
}

html {
  min-height: 100%;
  font-size: var(--font-base);
}

body {
  min-height: 100%;
  margin: 0;
  background:
    linear-gradient(180deg, rgba(55, 43, 31, 0.09), transparent 320px),
    repeating-linear-gradient(90deg, rgba(82, 61, 39, 0.018) 0 1px, transparent 1px 7px),
    var(--paper);
  color: var(--ink);
  font-family: Arial, Helvetica, sans-serif;
  font-size: var(--font-base);
  letter-spacing: 0;
}

button,
input,
select,
textarea {
  font: inherit;
  letter-spacing: 0;
}

.app-shell {
  width: min(1480px, calc(100% - 32px));
  margin: 0 auto;
  padding: 28px 0;
}

.app-header {
  position: relative;
  padding: 0 0 18px;
  margin-bottom: 22px;
  border-bottom: 1px solid rgba(140, 111, 69, 0.34);
  overflow: hidden;
  min-height: 142px;
}

.header-copy {
  position: relative;
  z-index: 1;
  width: 100%;
  padding-right: min(35%, 420px);
}

.brand-row {
  display: block;
}

.brand-row h1 {
  flex: 1 1 auto;
  min-width: 0;
}

.app-header h1 {
  margin: 0;
  font-size: var(--font-large);
  line-height: 1.05;
}

.app-header p {
  max-width: 980px;
  margin: 10px 0 0;
  color: var(--ink);
  font-size: var(--font-medium);
  font-weight: 400;
  line-height: 1.25;
}

.instrument-photo {
  position: absolute;
  z-index: 1;
  right: 0;
  top: 0;
  width: min(38%, 520px);
  margin: 0;
  overflow: hidden;
  pointer-events: none;
}

.instrument-photo img {
  display: block;
  width: 100%;
  height: auto;
  max-height: 168px;
  object-fit: contain;
  object-position: center;
  border: 0;
  border-radius: 0;
  background: transparent;
  box-shadow: none;
  opacity: 1;
}

.controls {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
  margin: 0;
}

.controls .control-group:nth-child(3) {
  grid-column: 1 / -1;
}

.control-group,
.fretboard-section {
  border: 1px solid var(--line);
  border-radius: 8px;
  background:
    linear-gradient(180deg, rgba(255, 253, 247, 0.96), rgba(248, 241, 228, 0.94)),
    var(--surface);
  box-shadow: 0 18px 42px rgba(55, 43, 31, 0.12), inset 0 1px 0 rgba(255, 255, 255, 0.72);
}

.control-group {
  padding: 12px;
}

.control-group h2 {
  margin: 0 0 10px;
  font-size: var(--font-medium);
  line-height: 1.12;
}

.button-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.structure-grid {
  display: grid;
  gap: 9px;
}

.structure-family {
  display: grid;
  gap: 5px;
  padding-top: 7px;
  border-top: 1px solid rgba(214, 203, 184, 0.82);
}

.structure-family:first-child {
  padding-top: 0;
  border-top: 0;
}

.structure-family-title {
  color: var(--muted);
  font-weight: 700;
  line-height: 1.1;
}

.structure-family.is-current-family .structure-family-title {
  color: #1c2822;
}

.structure-family-buttons {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 7px;
}

.control-button {
  min-height: 42px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background:
    linear-gradient(180deg, #fffdf8, #f4eadb),
    var(--surface);
  color: var(--ink);
  cursor: pointer;
  padding: 6px 12px;
  box-shadow: 0 5px 12px rgba(55, 43, 31, 0.07), inset 0 1px 0 rgba(255, 255, 255, 0.82);
  transition: background-color 160ms ease, border-color 160ms ease, color 160ms ease, transform 160ms ease;
}

.note-grid .control-button {
  min-width: 52px;
}

.structure-grid .control-button,
.mode-grid .control-button {
  min-width: 0;
  width: 100%;
}

.mode-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.mode-grid .control-button:last-child:nth-child(odd) {
  grid-column: 1 / -1;
}

.control-button:hover {
  border-color: #a88f67;
  box-shadow: 0 8px 16px rgba(55, 43, 31, 0.1), inset 0 1px 0 rgba(255, 255, 255, 0.88);
  transform: translateY(-1px);
}

.control-button:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 2px;
}

.control-button.is-active {
  border-color: #00b7ff;
  background:
    linear-gradient(180deg, #e7fbff, #9defff),
    #9defff;
  color: #053247;
  box-shadow: 0 0 0 2px rgba(0, 183, 255, 0.28), 0 0 20px rgba(0, 183, 255, 0.42), inset 0 1px 0 rgba(255, 255, 255, 0.78);
}

.learning-area {
  display: block;
  margin-bottom: 22px;
}

.study-workbench {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 10px;
  width: min(860px, 100%);
  margin: 0 auto;
}

.fretboard-section {
  min-width: 0;
  padding: 16px;
}

.active-combination {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  margin-bottom: 14px;
  color: var(--ink);
  font-size: var(--font-medium);
  font-weight: 400;
  line-height: 1.18;
}

.formula-card {
  display: inline-block;
  border: 1px solid rgba(110, 98, 80, 0.28);
  border-left: 5px solid #8c6f45;
  border-radius: 4px;
  background: rgba(255, 250, 240, 0.68);
  padding: 8px 12px;
  font-weight: 400;
  box-shadow: none;
}

.fretboard-scroll {
  overflow-x: auto;
  padding-bottom: 8px;
}

.fretboard-shell {
  --fret-columns:
    minmax(0, 0.68fr)
    minmax(0, 0.72fr)
    minmax(0, 0.76fr)
    minmax(0, 0.80fr)
    minmax(0, 0.84fr)
    minmax(0, 0.89fr)
    minmax(0, 0.94fr)
    minmax(0, 0.99fr)
    minmax(0, 1.05fr)
    minmax(0, 1.11fr)
    minmax(0, 1.17fr)
    minmax(0, 1.24fr);
  display: grid;
  grid-template-columns: minmax(792px, 1fr) 76px;
  min-width: 868px;
}

.headstock {
  display: grid;
  grid-template-rows: repeat(5, 62px);
  margin-top: 36px;
  border-radius: 0 8px 8px 0;
  background:
    linear-gradient(270deg, rgba(255, 255, 255, 0.09), transparent),
    linear-gradient(180deg, #32332f, #20231f);
  color: #f8fbf7;
  overflow: hidden;
}

.headstock strong {
  display: grid;
  place-items: center;
  border-top: 1px solid rgba(255, 255, 255, 0.14);
  font-size: var(--font-base);
}

.headstock strong:first-child {
  border-top: 0;
}

.headstock strong.is-support {
  color: rgba(248, 251, 247, 0.78);
}

.fretboard-body {
  min-width: 0;
}

.fret-numbers {
  display: grid;
  grid-template-columns: var(--fret-columns);
  height: 36px;
  color: var(--muted);
}

.fret-numbers span {
  display: grid;
  place-items: center;
  font-size: var(--font-base);
}

.fretboard-grid {
  position: relative;
  display: grid;
  grid-template-columns: var(--fret-columns);
  grid-template-rows: repeat(5, 62px);
  overflow: hidden;
  border: 2px solid var(--fretboard-dark);
  border-right: 0;
  border-radius: 8px 0 0 8px;
  background:
    linear-gradient(270deg, rgba(255, 255, 255, 0.1), transparent 32%, rgba(0, 0, 0, 0.18)),
    radial-gradient(ellipse at 18% 28%, rgba(151, 92, 49, 0.3), transparent 34%),
    radial-gradient(ellipse at 66% 72%, rgba(32, 22, 17, 0.32), transparent 42%),
    repeating-linear-gradient(7deg, rgba(255, 216, 165, 0.045) 0 2px, transparent 2px 11px),
    repeating-linear-gradient(90deg, rgba(92, 58, 37, 0.18) 0 9px, rgba(35, 24, 19, 0.12) 9px 18px, transparent 18px 28px),
    linear-gradient(180deg, #654635 0%, #4b362b 45%, #312821 100%);
}

.marker-layer {
  position: absolute;
  inset: 0;
  z-index: 1;
  display: grid;
  grid-template-columns: var(--fret-columns);
  pointer-events: none;
}

.marker-layer > span {
  position: relative;
}

.single-marker i,
.double-marker i {
  position: absolute;
  left: 50%;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: rgba(245, 246, 241, 0.34);
  transform: translate(-50%, -50%);
}

.single-marker i {
  top: 50%;
}

.double-marker i:first-child {
  top: 38%;
}

.double-marker i:last-child {
  top: 62%;
}

.fret-cell {
  position: relative;
  z-index: 2;
  display: grid;
  place-items: center;
  min-width: 0;
  background: linear-gradient(90deg, var(--fret) 0 3px, transparent 3px);
  --string-upper-size: 3px;
  --string-lower-size: 3px;
  --string-pair-gap: 5px;
}

.fret-cell.is-fret-1 {
  background:
    linear-gradient(90deg, var(--fret) 0 3px, transparent 3px calc(100% - 3px), var(--fret) calc(100% - 3px));
}

.fret-cell::before,
.fret-cell::after {
  content: "";
  position: absolute;
  left: -2px;
  right: -2px;
  z-index: 3;
  border-radius: 999px;
  background:
    repeating-linear-gradient(104deg, rgba(255, 255, 255, 0.58) 0 1px, rgba(132, 136, 128, 0.48) 1px 3px, rgba(39, 42, 39, 0.32) 3px 4px, rgba(235, 239, 232, 0.52) 4px 6px),
    linear-gradient(180deg, #ffffff 0%, var(--string) 38%, #7f8985 68%, #f4f8f5 100%);
  background-blend-mode: overlay, normal;
  box-shadow:
    0 1px 4px rgba(0, 0, 0, 0.55),
    inset 0 1px 0 rgba(255, 255, 255, 0.78),
    inset 0 -1px 0 rgba(39, 42, 39, 0.32);
  transform: translateY(-50%);
}

.fret-cell::before {
  top: calc(50% - var(--string-pair-gap));
  height: var(--string-upper-size);
}

.fret-cell::after {
  top: calc(50% + var(--string-pair-gap));
  height: var(--string-lower-size);
}

.fret-cell.string-name-a {
  --string-upper-size: 2px;
  --string-lower-size: 6px;
  --string-pair-gap: 5px;
}

.fret-cell.string-name-d {
  --string-upper-size: 2px;
  --string-lower-size: 5px;
  --string-pair-gap: 5px;
}

.fret-cell.string-name-g {
  --string-upper-size: 4px;
  --string-lower-size: 4px;
  --string-pair-gap: 5px;
}

.fret-cell.string-name-c {
  --string-upper-size: 3px;
  --string-lower-size: 3px;
  --string-pair-gap: 5px;
}

.fret-cell.string-name-f {
  --string-upper-size: 2px;
  --string-lower-size: 2px;
  --string-pair-gap: 5px;
}

.fret-cell.string-name-f::before,
.fret-cell.string-name-f::after {
  background-size: 8px 100%, auto;
}

.fret-cell.string-role-support::before,
.fret-cell.string-role-support::after {
  opacity: 0.68;
}

.note-token {
  position: relative;
  z-index: 4;
  display: grid;
  place-items: center;
  width: 56px;
  height: 56px;
  border: 2px solid rgba(255, 255, 255, 0.82);
  border-radius: 50%;
  background: var(--note);
  color: var(--note-ink);
  font-weight: 700;
  line-height: 1;
  box-shadow: 0 10px 18px rgba(0, 0, 0, 0.28);
}

.note-token span {
  font-size: var(--font-base);
}

.note-token.is-root {
  width: 62px;
  height: 62px;
  border-color: #fff2b7;
  background: var(--root);
  color: var(--root-ink);
  box-shadow: 0 0 0 5px rgba(255, 207, 74, 0.28), 0 12px 22px rgba(0, 0, 0, 0.32);
}

.note-token.is-support-string {
  opacity: 0.74;
  filter: saturate(0.78);
  box-shadow: 0 7px 12px rgba(0, 0, 0, 0.22);
}

.note-token.is-support-string.is-root {
  opacity: 0.9;
  filter: saturate(0.92);
  box-shadow: 0 0 0 3px rgba(255, 207, 74, 0.2), 0 8px 14px rgba(0, 0, 0, 0.24);
}

.note-token.is-octave-root {
  border-color: #ffffff;
  box-shadow: 0 0 0 5px rgba(255, 207, 74, 0.34), 0 0 0 9px rgba(120, 211, 231, 0.24), 0 12px 22px rgba(0, 0, 0, 0.32);
}

@media (max-width: 980px) {
  .study-workbench {
    width: 100%;
  }
}

@media (max-width: 620px) {
  .app-shell {
    width: min(100% - 14px, 1480px);
    padding: 12px 0;
  }

  .app-header {
    padding-bottom: 12px;
    margin-bottom: 14px;
    min-height: 122px;
  }

  .header-copy {
    padding-right: 150px;
  }

  .app-header p {
    margin-top: 8px;
    line-height: 1.18;
  }

  .instrument-photo {
    width: 146px;
    right: 0;
    top: 0;
  }

  .instrument-photo img {
    max-height: 72px;
    opacity: 1;
  }

  .control-group,
  .fretboard-section {
    padding: 10px;
  }

  .learning-area,
  .study-workbench {
    gap: 14px;
  }

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

  .controls .control-group:nth-child(3) {
    grid-column: auto;
    grid-row: auto;
  }

  .mode-grid,
  .structure-family-buttons {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .control-group h2 {
    margin-bottom: 8px;
  }

  .control-button {
    min-height: 40px;
    padding: 5px 8px;
  }

  .fretboard-scroll {
    margin-inline: -4px;
    padding-bottom: 10px;
    scrollbar-width: thin;
  }

  .fretboard-scroll::-webkit-scrollbar {
    height: 10px;
  }

  .fretboard-scroll::-webkit-scrollbar-thumb {
    border-radius: 999px;
    background: rgba(55, 43, 31, 0.32);
  }

  .active-combination {
    gap: 8px;
    margin-bottom: 10px;
    overflow-wrap: anywhere;
  }

  .formula-card {
    flex: 1 1 100%;
    padding: 6px 8px;
  }

  .fretboard-shell {
    grid-template-columns: minmax(624px, 1fr) 54px;
    min-width: 678px;
  }

  .headstock {
    grid-template-rows: repeat(5, 50px);
    margin-top: 30px;
  }

  .fret-numbers {
    grid-template-columns: var(--fret-columns);
    height: 30px;
  }

  .fretboard-grid {
    grid-template-columns: var(--fret-columns);
    grid-template-rows: repeat(5, 50px);
  }

  .fret-cell {
    min-width: 0;
    --string-pair-gap: 4px;
  }

  .note-token {
    width: 50px;
    height: 50px;
  }

  .note-token.is-root {
    width: 56px;
    height: 56px;
  }
}