/* =========================================================================
   Fretwork — a luthier's-workshop palette: warm paper, espresso ink, amber.
   ========================================================================= */
:root {
  --paper: #f3e9d8;
  --paper-2: #ece0c9;
  --card: #fbf5e9;
  --ink: #2a2018;
  --ink-soft: #5d4f40;
  --line: #d8c7a8;
  --amber: #c25b29;
  --amber-deep: #9c3f17;
  --gold: #d99a2b;
  --sage: #5e6f4e;
  --shadow: 24px 24px 0 rgba(42, 32, 24, 0.06);
  --radius: 18px;
  --maxw: 1080px;
  --display: "Fraunces", Georgia, serif;
  --body: "Spline Sans", system-ui, sans-serif;
  --mono: "Spline Sans Mono", ui-monospace, monospace;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--body);
  color: var(--ink);
  background: var(--paper);
  background-image: radial-gradient(circle at 18% 8%, rgba(217, 154, 43, 0.14), transparent 42%),
    radial-gradient(circle at 88% 0%, rgba(194, 91, 41, 0.1), transparent 38%);
  background-attachment: fixed;
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
}

/* film grain overlay */
.grain {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 1;
  opacity: 0.5;
  mix-blend-mode: multiply;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='120' height='120'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='2' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)' opacity='0.45'/%3E%3C/svg%3E");
}

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

::selection { background: var(--amber); color: #fff; }

/* ---------- top bar ---------- */
.topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.9rem clamp(1rem, 4vw, 3rem);
  background: rgba(243, 233, 216, 0.82);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}
.brand { display: flex; align-items: center; gap: 0.55rem; }
.brand__mark { color: var(--amber); font-size: 1.4rem; transform: translateY(1px); }
.brand__name {
  font-family: var(--display);
  font-weight: 900;
  font-size: 1.4rem;
  letter-spacing: -0.02em;
}
.nav { display: flex; gap: clamp(0.6rem, 2vw, 1.8rem); }
.nav-link {
  font-size: 0.92rem;
  font-weight: 500;
  color: var(--ink-soft);
  padding: 0.3rem 0;
  border-bottom: 2px solid transparent;
  transition: color 0.18s, border-color 0.18s;
}
.nav-link:hover { color: var(--ink); }
.nav-link.is-active { color: var(--amber-deep); border-color: var(--amber); }

/* ---------- layout ---------- */
#app {
  position: relative;
  z-index: 2;
  max-width: var(--maxw);
  margin: 0 auto;
  padding: clamp(1.6rem, 5vw, 4rem) clamp(1rem, 4vw, 2rem) 4rem;
}
.section { margin-top: clamp(2.5rem, 6vw, 4.5rem); }
.section__head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 1.4rem;
  border-bottom: 1px solid var(--line);
  padding-bottom: 0.6rem;
}
.section__title, .fam-title {
  font-family: var(--display);
  font-size: clamp(1.4rem, 3vw, 2rem);
  font-weight: 600;
  margin: 0;
}
.fam-title { margin-bottom: 1.2rem; }
.section__more { font-size: 0.9rem; color: var(--amber-deep); font-weight: 500; }
.section__more:hover { text-decoration: underline; }

/* ---------- hero ---------- */
.hero { max-width: 780px; }
.hero__eyebrow {
  font-family: var(--mono);
  text-transform: uppercase;
  letter-spacing: 0.22em;
  font-size: 0.72rem;
  color: var(--amber-deep);
  margin: 0 0 1rem;
}
.hero__title {
  font-family: var(--display);
  font-weight: 900;
  font-size: clamp(2.6rem, 8vw, 5rem);
  line-height: 0.98;
  letter-spacing: -0.03em;
  margin: 0 0 1.4rem;
}
.hero__title em {
  font-style: italic;
  font-weight: 500;
  color: var(--amber);
}
.hero__lead {
  font-size: clamp(1.05rem, 2vw, 1.25rem);
  color: var(--ink-soft);
  max-width: 60ch;
  margin: 0 0 2rem;
}
.hero__cta { display: flex; gap: 0.8rem; flex-wrap: wrap; }

/* ---------- buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-family: var(--body);
  font-weight: 600;
  font-size: 0.98rem;
  padding: 0.7rem 1.3rem;
  border-radius: 100px;
  border: 1.5px solid var(--ink);
  cursor: pointer;
  transition: transform 0.12s ease, box-shadow 0.12s, background 0.15s, color 0.15s;
}
.btn:active { transform: translateY(1px); }
.btn--solid { background: var(--ink); color: var(--paper); }
.btn--solid:hover { background: var(--amber-deep); border-color: var(--amber-deep); }
.btn--ghost { background: transparent; color: var(--ink); }
.btn--ghost:hover { background: var(--ink); color: var(--paper); }
.btn:disabled { opacity: 0.35; cursor: not-allowed; }

/* ---------- tool cards ---------- */
.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.2rem;
}
.tool-card {
  position: relative;
  background: var(--card);
  border: 1.5px solid var(--ink);
  border-radius: var(--radius);
  padding: 1.6rem 1.5rem 1.4rem;
  box-shadow: var(--shadow);
  overflow: hidden;
  transition: transform 0.18s ease, box-shadow 0.18s;
}
.tool-card::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, transparent 60%, rgba(194, 91, 41, 0.08));
  pointer-events: none;
}
.tool-card:hover { transform: translate(-4px, -4px); box-shadow: 30px 30px 0 rgba(42, 32, 24, 0.08); }
.tool-card__num {
  font-family: var(--display);
  font-style: italic;
  font-size: 2.4rem;
  font-weight: 500;
  color: var(--amber);
  line-height: 1;
}
.tool-card__title {
  font-family: var(--display);
  font-size: 1.5rem;
  font-weight: 600;
  margin: 0.6rem 0 0.5rem;
}
.tool-card__desc { color: var(--ink-soft); margin: 0 0 1.1rem; font-size: 0.97rem; }
.tool-card__go { font-weight: 600; color: var(--amber-deep); font-size: 0.92rem; }

/* ---------- chord grid + cards ---------- */
.chord-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
  gap: 1rem;
}
.chord-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.4rem;
  background: var(--card);
  border: 1.5px solid var(--line);
  border-radius: 14px;
  transition: transform 0.16s ease, border-color 0.16s, box-shadow 0.16s;
}
.chord-card:hover {
  transform: translateY(-4px);
  border-color: var(--amber);
  box-shadow: 0 12px 0 -4px rgba(194, 91, 41, 0.18);
}
.chord-card__name {
  font-family: var(--display);
  font-weight: 600;
  font-size: 1.05rem;
}
.chord-card__play {
  margin: 0.1rem 0 0.9rem;
  padding: 0.3rem 0.8rem;
  font-size: 0.85rem;
}

/* ---------- chord diagram svg ---------- */
.chord-diagram { display: block; max-width: 100%; height: auto; margin-inline: auto; }
.cd-nut { fill: var(--ink); }
.cd-fret, .cd-string { stroke: var(--ink-soft); stroke-width: 1.4; }
.cd-dot { fill: var(--ink); }
.cd-finger { fill: var(--paper); font-family: var(--mono); font-weight: 600; font-size: 13px; text-anchor: middle; dominant-baseline: central; }
.cd-open { fill: none; stroke: var(--ink); stroke-width: 1.6; }
.cd-mark { font-family: var(--mono); font-size: 15px; text-anchor: middle; dominant-baseline: central; }
.cd-mute { fill: var(--ink-soft); }
.cd-strlabel { font-family: var(--mono); font-size: 11px; fill: var(--ink-soft); text-anchor: middle; }
.cd-basefret { font-family: var(--mono); font-size: 11px; fill: var(--ink-soft); text-anchor: end; }

/* ---------- page heads ---------- */
.page-head { margin-bottom: 2rem; max-width: 70ch; }
.page-head__title {
  font-family: var(--display);
  font-weight: 900;
  font-size: clamp(2rem, 6vw, 3.4rem);
  letter-spacing: -0.02em;
  line-height: 1.02;
  margin: 0 0 0.8rem;
}
.page-head__lead { color: var(--ink-soft); font-size: 1.08rem; margin: 0; }
.backlink { display: inline-block; margin-bottom: 1.4rem; color: var(--amber-deep); font-weight: 500; }
.backlink:hover { text-decoration: underline; }

/* ---------- chord detail ---------- */
.detail-head {
  display: grid;
  grid-template-columns: minmax(220px, 320px) 1fr;
  gap: clamp(1.5rem, 5vw, 3.5rem);
  align-items: start;
}
.detail-diagram {
  background: var(--card);
  border: 1.5px solid var(--ink);
  border-radius: var(--radius);
  padding: 1.4rem;
  box-shadow: var(--shadow);
  display: flex;
  justify-content: center;
}
.detail-diagram-col {
  display: flex;
  flex-direction: column;
  align-items: center;
}
.detail-diagram-col .detail-diagram { width: 100%; }
.detail-diagram__play { margin-top: 1rem; }
.detail-kicker {
  font-family: var(--mono);
  text-transform: uppercase;
  letter-spacing: 0.18em;
  font-size: 0.72rem;
  color: var(--amber-deep);
  margin: 0 0 0.4rem;
}
.detail-title {
  font-family: var(--display);
  font-weight: 900;
  font-size: clamp(2.4rem, 7vw, 4rem);
  margin: 0 0 1rem;
  letter-spacing: -0.02em;
}
.detail-tip { font-size: 1.08rem; color: var(--ink-soft); max-width: 52ch; margin: 0 0 1.6rem; }
.detail-actions { display: flex; gap: 0.7rem; flex-wrap: wrap; margin-top: 1.6rem; }

.fingering { list-style: none; margin: 0; padding: 0; display: grid; gap: 0.3rem; max-width: 340px; }
.fingering li {
  display: flex;
  align-items: center;
  gap: 0.9rem;
  padding: 0.45rem 0.7rem;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 10px;
  font-size: 0.95rem;
}
.fingering li.is-mute { opacity: 0.55; }
.fingering__str {
  font-family: var(--mono);
  font-weight: 600;
  width: 1.4rem;
  text-align: center;
  color: var(--amber-deep);
}
.fingering__act { color: var(--ink-soft); }

/* ---------- pickers / selects ---------- */
.picker { display: flex; flex-direction: column; gap: 0.35rem; }
.picker__label {
  font-family: var(--mono);
  text-transform: uppercase;
  letter-spacing: 0.14em;
  font-size: 0.68rem;
  color: var(--ink-soft);
}
.select {
  font-family: var(--display);
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--ink);
  background: var(--card);
  border: 1.5px solid var(--ink);
  border-radius: 12px;
  padding: 0.55rem 2.2rem 0.55rem 0.9rem;
  cursor: pointer;
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='14' height='14' viewBox='0 0 14 14'%3E%3Cpath d='M3 5l4 4 4-4' stroke='%232a2018' stroke-width='1.6' fill='none'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0.8rem center;
}

/* ---------- practice ---------- */
.practice-panel {
  display: grid;
  grid-template-columns: minmax(220px, 300px) 1fr;
  gap: clamp(1.5rem, 5vw, 3rem);
  align-items: start;
  margin-top: 1.8rem;
}
.practice-diagram {
  background: var(--card);
  border: 1.5px solid var(--ink);
  border-radius: var(--radius);
  padding: 1.4rem;
  box-shadow: var(--shadow);
  text-align: center;
  position: sticky;
  top: 90px;
}
.practice-diagram__name { font-family: var(--display); font-weight: 600; font-size: 1.3rem; margin: 0.6rem 0 0; }
.practice-diagram__play { margin-top: 1rem; }

.stepper__nav { display: flex; flex-wrap: wrap; gap: 0.5rem; margin-bottom: 1.4rem; }
.stepper__tab {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--card);
  border: 1.5px solid var(--line);
  border-radius: 100px;
  padding: 0.4rem 0.9rem 0.4rem 0.4rem;
  cursor: pointer;
  font-family: var(--body);
  font-size: 0.85rem;
  color: var(--ink-soft);
  transition: all 0.15s;
}
.stepper__no {
  display: grid;
  place-items: center;
  width: 1.5rem;
  height: 1.5rem;
  border-radius: 50%;
  background: var(--paper-2);
  font-family: var(--mono);
  font-weight: 600;
  color: var(--ink);
}
.stepper__tab.is-active { border-color: var(--ink); color: var(--ink); background: var(--card); }
.stepper__tab.is-active .stepper__no { background: var(--amber); color: #fff; }
.stepper__tab.is-done .stepper__no { background: var(--sage); color: #fff; }
.stepper__name { display: none; }
@media (min-width: 620px) { .stepper__name { display: inline; } }

.step-body {
  background: var(--card);
  border: 1.5px solid var(--ink);
  border-radius: var(--radius);
  padding: clamp(1.4rem, 4vw, 2.2rem);
  box-shadow: var(--shadow);
}
.step-body__count {
  font-family: var(--mono);
  text-transform: uppercase;
  letter-spacing: 0.16em;
  font-size: 0.7rem;
  color: var(--amber-deep);
  margin: 0 0 0.5rem;
}
.step-body__title { font-family: var(--display); font-size: clamp(1.6rem, 4vw, 2.3rem); font-weight: 600; margin: 0 0 0.7rem; }
.step-body__text { color: var(--ink-soft); font-size: 1.08rem; margin: 0 0 1.6rem; max-width: 56ch; }
.step-body__controls { display: flex; gap: 0.7rem; }

/* ---------- one-minute changes ---------- */
.changes-pickers {
  display: flex;
  align-items: flex-end;
  gap: 1.2rem;
  flex-wrap: wrap;
  margin-bottom: 2rem;
}
.changes-arrow { font-size: 1.6rem; color: var(--amber); padding-bottom: 0.4rem; }
.changes-pair {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: clamp(1rem, 5vw, 3rem);
  flex-wrap: wrap;
  background: var(--card);
  border: 1.5px solid var(--ink);
  border-radius: var(--radius);
  padding: clamp(1.4rem, 4vw, 2.4rem);
  box-shadow: var(--shadow);
}
.changes-swap { font-size: 2.4rem; color: var(--amber); font-family: var(--display); }
.changes-diagram { text-align: center; }
.changes-diagram__name { font-family: var(--display); font-weight: 600; font-size: 1.4rem; margin: 0.6rem 0 0; }

.changes-meters {
  display: flex;
  gap: 1.2rem;
  flex-wrap: wrap;
  margin-top: 1.4rem;
}
.clock, .counter {
  flex: 1 1 200px;
  background: var(--ink);
  color: var(--paper);
  border: none;
  border-radius: var(--radius);
  padding: 1.4rem 1.2rem;
  text-align: center;
  font-family: var(--mono);
}
.clock__time { font-size: clamp(3rem, 12vw, 4.6rem); font-weight: 600; letter-spacing: -0.02em; display: block; line-height: 1; }
.counter { cursor: pointer; transition: transform 0.1s; background: var(--amber-deep); }
.counter:hover { transform: translateY(-2px); }
.counter__num { font-size: clamp(3rem, 12vw, 4.6rem); font-weight: 600; display: block; line-height: 1; }
.counter__lbl { text-transform: uppercase; letter-spacing: 0.2em; font-size: 0.7rem; opacity: 0.8; }
.counter.pulse { animation: pop 0.25s ease; }
.counter.done { background: var(--sage); }
@keyframes pop { 0% { transform: scale(1); } 40% { transform: scale(1.06); } 100% { transform: scale(1); } }

.changes-controls { display: flex; gap: 0.7rem; margin-top: 1.2rem; }
.changes-hint { margin-top: 1.2rem; color: var(--ink-soft); font-size: 0.92rem; }
.changes-hint .soon { display: block; margin-top: 0.3rem; font-style: italic; opacity: 0.8; }

kbd {
  font-family: var(--mono);
  background: var(--card);
  border: 1px solid var(--line);
  border-bottom-width: 2px;
  border-radius: 6px;
  padding: 0.05rem 0.4rem;
  font-size: 0.85em;
}

/* drilling state — subtle pulse on the clock */
body.is-drilling .clock { animation: breathe 2s ease-in-out infinite; }
@keyframes breathe {
  0%, 100% { box-shadow: 0 0 0 0 rgba(194, 91, 41, 0); }
  50% { box-shadow: 0 0 0 6px rgba(194, 91, 41, 0.18); }
}

/* ---------- footer ---------- */
.footer {
  position: relative;
  z-index: 2;
  text-align: center;
  padding: 2.5rem 1rem 3rem;
  color: var(--ink-soft);
  font-size: 0.9rem;
  border-top: 1px solid var(--line);
  margin-top: 2rem;
}
.footer a { color: var(--amber-deep); text-decoration: underline; }

/* ---------- reveal animation ---------- */
.reveal { opacity: 0; transform: translateY(14px); transition: opacity 0.5s ease, transform 0.5s ease; transition-delay: var(--d, 0ms); }
.reveal.in { opacity: 1; transform: none; }
@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
  * { animation: none !important; }
}

/* ---------- tuner ---------- */
.tuner-unsupported {
  background: var(--card);
  border: 1.5px solid var(--line);
  border-radius: var(--radius);
  padding: 1.2rem 1.4rem;
  color: var(--ink-soft);
  margin-top: 1.5rem;
}
.tuner-stage {
  display: grid;
  grid-template-columns: minmax(240px, 360px) 1fr;
  gap: clamp(1.5rem, 4vw, 3rem);
  align-items: start;
  margin-top: 1.8rem;
}
.tuner-head { display: flex; justify-content: center; }
.headstock { width: 100%; max-width: 340px; height: auto; }

.hs-body {
  fill: var(--card);
  stroke: var(--ink);
  stroke-width: 2.5;
  filter: drop-shadow(8px 10px 0 rgba(42, 32, 24, 0.06));
}
.hs-nut { fill: var(--ink-soft); }
.hs-string { stroke: var(--ink-soft); transition: stroke 0.2s; }
.hs-string.is-active { stroke: var(--amber); }

.hs-key { fill: var(--paper-2); stroke: var(--ink); stroke-width: 1.5; transition: fill 0.2s; }
.hs-key-cap { fill: var(--paper-2); stroke: var(--ink); stroke-width: 1.5; transition: fill 0.2s; }
.hs-peg-ring { fill: var(--paper-2); stroke: var(--ink); stroke-width: 1.5; transition: fill 0.2s; }
.hs-peg-head { fill: var(--card); stroke: var(--ink); stroke-width: 1.5; transition: fill 0.2s, stroke 0.2s; }
.hs-peg-note {
  font-family: var(--display);
  font-weight: 900;
  font-size: 14px;
  fill: var(--ink);
  text-anchor: middle;
  pointer-events: none;
  transition: fill 0.2s;
}
.hs-peg:hover .hs-peg-head { stroke: var(--amber); }
.hs-peg:hover .hs-peg-ring { fill: var(--paper); }
.hs-peg.is-active .hs-peg-head { fill: var(--amber); stroke: var(--amber-deep); }
.hs-peg.is-active .hs-peg-ring { fill: var(--amber-deep); }
.hs-peg.is-active .hs-peg-note { fill: var(--paper); }
.hs-peg.is-active .hs-key,
.hs-peg.is-active .hs-key-cap { fill: var(--amber); stroke: var(--amber-deep); }
.hs-peg:focus { outline: none; }
.hs-peg:focus-visible .hs-peg-ring { fill: var(--gold); }

/* readout panel */
.tuner-readout {
  background: var(--card);
  border: 1.5px solid var(--line);
  border-radius: var(--radius);
  padding: clamp(1.2rem, 3vw, 2rem);
  box-shadow: var(--shadow);
}
.tuner-readout__label {
  font-family: var(--mono);
  text-transform: uppercase;
  letter-spacing: 0.16em;
  font-size: 0.68rem;
  color: var(--ink-soft);
  margin: 0;
}
.tuner-note {
  font-family: var(--display);
  font-weight: 900;
  font-size: clamp(4rem, 16vw, 6rem);
  line-height: 1;
  margin: 0.2rem 0 0;
}
.tuner-sci {
  font-family: var(--mono);
  color: var(--ink-soft);
  font-size: 0.9rem;
  margin-bottom: 1.5rem;
}

/* gauge */
.gauge { margin: 0.5rem 0 1.2rem; }
.gauge__scale {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-family: var(--mono);
  color: var(--ink-soft);
  font-size: 1.1rem;
  margin-bottom: 0.3rem;
}
.gauge__center {
  width: 2px;
  height: 12px;
  background: var(--ink-soft);
  border-radius: 2px;
}
.gauge__track {
  position: relative;
  height: 16px;
  border-radius: 999px;
  background: linear-gradient(90deg,
    rgba(194, 91, 41, 0.25) 0%,
    rgba(94, 111, 78, 0.25) 50%,
    rgba(194, 91, 41, 0.25) 100%);
  border: 1.5px solid var(--line);
}
.gauge__track::before {
  content: "";
  position: absolute;
  left: 50%;
  top: -3px;
  bottom: -3px;
  width: 2px;
  background: var(--ink);
  transform: translateX(-50%);
  opacity: 0.4;
}
.gauge__needle {
  position: absolute;
  top: -5px;
  bottom: -5px;
  left: 50%;
  width: 4px;
  border-radius: 3px;
  background: var(--ink-soft);
  transform: translateX(-50%);
  transition: left 0.09s linear, background 0.2s;
}
.gauge.is-intune .gauge__needle { background: var(--sage); }
.gauge.is-flat .gauge__needle,
.gauge.is-sharp .gauge__needle { background: var(--amber); }
.gauge__legend {
  display: flex;
  justify-content: space-between;
  font-family: var(--mono);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  font-size: 0.62rem;
  color: var(--ink-soft);
  margin-top: 0.4rem;
}

.tuner-instruction {
  display: block;
  width: 100%;
  font-family: var(--display);
  font-weight: 600;
  font-size: 1.3rem;
  padding: 0.9rem 1rem;
  border-radius: 12px;
  border: 1.5px solid var(--ink);
  background: var(--paper-2);
  color: var(--ink);
  text-align: center;
  cursor: pointer;
  transition: background 0.2s, color 0.2s, transform 0.1s;
}
.tuner-instruction:hover { transform: translateY(-2px); }
.tuner-instruction.is-loading { opacity: 0.6; pointer-events: none; }
.tuner-instruction.is-on { background: var(--card); }
.tuner-instruction.is-intune { background: var(--sage); color: var(--paper); border-color: var(--sage); }
.tuner-instruction.is-flat,
.tuner-instruction.is-sharp { background: var(--amber); color: var(--paper); border-color: var(--amber); }

.tuner-freq {
  font-family: var(--mono);
  color: var(--ink-soft);
  text-align: center;
  font-size: 0.9rem;
  margin: 0.7rem 0 1.2rem;
}

/* ---------- responsive ---------- */
@media (max-width: 760px) {
  .detail-head, .practice-panel { grid-template-columns: 1fr; }
  .practice-diagram { position: static; }
  .nav { gap: 0.8rem; flex-wrap: wrap; }
  .tuner-stage { grid-template-columns: 1fr; }
  .tuner-head { order: -1; }
  .headstock { max-width: 280px; }
}