/* Longtai Pro Audio — hero drawing sheets.
   All colours and line weights are variables on .lt-sheets; override them on the container
   or on :root. The site is black, white and grey only: no accent colour. */

.lt-sheets {
  --lt-paper: #ffffff;              /* sheet background */
  --lt-edge: rgba(0, 0, 0, 0.08);   /* hairline around the sheet */
  --lt-ink: #171717;                /* thick and medium lines, main text */
  --lt-ink-2: #4d4d4d;              /* thin lines */
  --lt-ink-3: #8e8e8c;              /* dimensions, leaders, hatching, secondary text */
  --lt-ink-4: #d4d4d1;              /* graph grid */
  --lt-font-hand: "Architects Daughter", "Noto Sans TC", "PingFang TC", sans-serif;
  /* digits: Architects Daughter draws 1 like a capital I (AD15 reads ADI5) */
  --lt-font-digit: "Patrick Hand", var(--lt-font-hand);
  --lt-font-ui: inherit;

  /* line weights in sheet units (840 units across) */
  --lt-w-thick: 2.3;
  --lt-w-med: 1.5;
  --lt-w-thin: 1;
  --lt-w-dim: 0.8;
  --lt-w-spk: 3;

  container-type: inline-size;
  position: relative;
  display: grid;
  gap: 10px;
  width: 100%;
}

/* narrow containers: the sheet is drawn small, so lines get relatively heavier */
@container (max-width: 520px) {
  .lt-stage {
    --lt-w-thick: 3.2;
    --lt-w-med: 2.1;
    --lt-w-thin: 1.4;
    --lt-w-dim: 1.2;
    --lt-w-spk: 4;
  }
}

.lt-stage {
  position: relative;
  aspect-ratio: 840 / 594;
  background: var(--lt-paper);
  box-shadow: 0 0 0 1px var(--lt-edge);
}
.lt-sheet {
  position: absolute;
  inset: 0;
  opacity: 0;
  visibility: hidden;
}
.lt-sheet.is-on { opacity: 1; visibility: visible; }
.lt-sheet-svg { display: block; width: 100%; height: 100%; overflow: visible; }

/* ---------- lines ---------- */
.lt-sheet-svg :is(path, rect, circle, line, polyline, polygon) {
  fill: none;
  stroke: var(--lt-ink);
  stroke-linecap: round;
  stroke-linejoin: round;
}
.lt-sheet-svg .ln-thick { stroke-width: var(--lt-w-thick); }
.lt-sheet-svg .ln-med { stroke-width: var(--lt-w-med); }
.lt-sheet-svg .ln-thin { stroke-width: var(--lt-w-thin); stroke: var(--lt-ink-2); }
.lt-sheet-svg .ln-dim, .lt-sheet-svg .ln-tick { stroke-width: var(--lt-w-dim); stroke: var(--lt-ink-3); }
.lt-sheet-svg .ln-tick { stroke-width: calc(var(--lt-w-dim) * 1.8); stroke: var(--lt-ink-2); }
.lt-sheet-svg .ln-grid { stroke-width: var(--lt-w-dim); stroke: var(--lt-ink-4); }
.lt-sheet-svg .ln-hidden { stroke-width: var(--lt-w-med); stroke: var(--lt-ink-2); stroke-dasharray: 6 4; stroke-linecap: butt; }
.lt-sheet-svg .ln-center { stroke-width: var(--lt-w-dim); stroke: var(--lt-ink-3); stroke-dasharray: 20 4 3 4; stroke-linecap: butt; }
.lt-sheet-svg .ln-cov { stroke-width: var(--lt-w-thin); stroke: var(--lt-ink-2); stroke-dasharray: 4 5; }
.lt-sheet-svg .ln-aim { stroke-width: var(--lt-w-med); stroke: var(--lt-ink); stroke-dasharray: 8 5; stroke-linecap: butt; }
.lt-sheet-svg .ln-net { stroke-width: var(--lt-w-thin); stroke: var(--lt-ink-2); stroke-dasharray: 7 4; stroke-linecap: butt; }
.lt-sheet-svg .ln-zone { stroke-width: var(--lt-w-dim); stroke: var(--lt-ink-3); stroke-dasharray: 14 4 2 4; stroke-linecap: butt; }
.lt-sheet-svg .ln-spk { stroke-width: var(--lt-w-spk); stroke: var(--lt-ink); }
.lt-sheet-svg .ar { fill: var(--lt-ink-2); stroke: none; }
.lt-sheet-svg .cut { stroke-width: var(--lt-w-thick); }
.lt-sheet-svg mask * { stroke: #fff; stroke-width: 8; stroke-dasharray: none; stroke-linecap: square; }
.lt-sheet-svg .hatch-line { stroke: var(--lt-ink-3); stroke-width: 0.7; }

/* ---------- lettering ---------- */
.lt-sheet-svg text {
  font-family: var(--lt-font-hand);
  fill: var(--lt-ink);
  stroke: none;
  letter-spacing: 0.02em;
}
.lt-sheet-svg .tx-xs { font-size: 8.5px; }
.lt-sheet-svg .tx-s { font-size: 11px; }
.lt-sheet-svg .tx { font-size: 13px; }
.lt-sheet-svg .tx-m { font-size: 15px; }
.lt-sheet-svg .tx-l { font-size: 20px; }
.lt-sheet-svg .dg { font-family: var(--lt-font-digit); }
.lt-sheet-svg text.soft { fill: var(--lt-ink-3); }
.lt-sheet-svg .dim text { fill: var(--lt-ink-2); }

/* ---------- caption ---------- */
.lt-caption {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  font-family: var(--lt-font-ui);
  font-size: 0.8125rem;
  color: var(--lt-ink-3);
  letter-spacing: 0.02em;
}
.lt-caption-bars { display: flex; gap: 6px; }
.lt-caption-bars i {
  display: block;
  width: 20px;
  height: 2px;
  background: var(--lt-ink-4);
  transition: background-color 300ms ease;
}
.lt-caption-bars i.is-on { background: var(--lt-ink); }

@media (prefers-reduced-motion: reduce) {
  .lt-caption-bars i { transition: none; }
}