/* ── tokens ── */
:root {
  --bg:          #f7f7f6;
  --surface:     #ffffff;
  --surface-2:   #f3f3f1;
  --border:      #e8e8e5;
  --border-mid:  #d6d6d1;
  --ink:         #18181a;
  --ink-2:       #5a5a55;
  --ink-3:       #9d9d96;
  --accent:      #2f5eff;
  --accent-soft: #eff2ff;
  --accent-dim:  #c5cfff;
  --teal:        #0ea88e;
  --teal-soft:   #e2f6f1;
  --red:         #e54444;
  --red-soft:    #fdeaea;
  --amber:       #f59e0b;
  --amber-soft:  #fff8e6;
  --loaded-border: #2f5eff;
  --loaded-bg:   #f5f7ff;
  --muted-bg:    #fafaf8;
  --r:           10px;
  --r-sm:        7px;
  --shadow-sm:   0 1px 3px rgba(0,0,0,.06), 0 1px 2px rgba(0,0,0,.04);
  --shadow-md:   0 4px 16px rgba(0,0,0,.07), 0 1px 3px rgba(0,0,0,.05);
  --f-disp: 'Space Grotesk', sans-serif;
  --f-body: 'IBM Plex Sans', sans-serif;
  --f-mono: 'IBM Plex Mono', monospace;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
body { background: var(--bg); color: var(--ink); font-family: var(--f-body); }
::selection { background: var(--accent-soft); color: var(--accent); }

/* ── root wrap ── */
.mixer-root {
  max-width: 1040px;
  margin: 0 auto;
}

/* ── top bar ── */
.mixer-topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 20px;
  gap: 12px;
  flex-wrap: wrap;
}
.mix-status {
  font-family: var(--f-mono);
  font-size: 11.5px;
  color: var(--ink-3);
  letter-spacing: .2px;
  flex: 1;
}
.topbar-right {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}
.track-count-badge {
  font-family: var(--f-mono);
  font-size: 10px;
  font-weight: 600;
  letter-spacing: .5px;
  color: var(--ink-3);
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 4px 10px;
  white-space: nowrap;
}
.engine-pill {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: var(--f-mono);
  font-size: 10.5px;
  color: var(--ink-3);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 4px 10px;
  white-space: nowrap;
}
.engine-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--ink-3);
  flex-shrink: 0;
}
.engine-pill.loading .engine-dot { background: var(--accent); animation: pulse 1.2s ease-in-out infinite; }
.engine-pill.loading { color: var(--accent); border-color: var(--accent-dim); }
.engine-pill.ready   .engine-dot { background: var(--teal); }
.engine-pill.ready   { color: var(--teal); border-color: #b3ead9; }
.engine-pill.error   .engine-dot { background: var(--red); }
.engine-pill.error   { color: var(--red); border-color: #f5c6c6; }
@keyframes pulse { 0%,100% { opacity: 1; } 50% { opacity: .3; } }

/* ── track grid — 4 columns, NO horizontal scroll ── */
.tracks-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
  margin-bottom: 20px;
}
@media (max-width: 840px)  { .tracks-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 440px)  { .tracks-grid { grid-template-columns: 1fr 1fr; } }

/* ── add-track card ── */
.track-add-card {
  border: 2px dashed var(--border-mid);
  border-radius: var(--r);
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 200px;
  cursor: pointer;
  transition: border-color .18s, background .18s;
  outline: none;
}
.track-add-card:hover,
.track-add-card:focus-visible {
  border-color: var(--accent);
  background: var(--accent-soft);
}
.add-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 9px;
}
.add-icon-wrap {
  width: 46px;
  height: 46px;
  border-radius: 50%;
  background: var(--surface-2);
  border: 1.5px solid var(--border-mid);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--ink-3);
  transition: background .18s, border-color .18s, color .18s;
}
.track-add-card:hover .add-icon-wrap,
.track-add-card:focus-visible .add-icon-wrap {
  background: var(--accent-soft);
  border-color: var(--accent);
  color: var(--accent);
}
.add-label {
  font-family: var(--f-mono);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: .6px;
  text-transform: uppercase;
  color: var(--ink-3);
  transition: color .18s;
}
.track-add-card:hover .add-label,
.track-add-card:focus-visible .add-label { color: var(--accent); }
.add-sub {
  font-family: var(--f-mono);
  font-size: 10px;
  color: var(--ink-3);
}

/* ── card entrance animation ── */
@keyframes cardIn {
  from { opacity: 0; transform: translateY(10px) scale(.97); }
  to   { opacity: 1; transform: none; }
}

/* ── track card ── */
.track-card {
  animation: cardIn .22s cubic-bezier(.22,.68,0,1.2) both;
  background: var(--surface);
  border: 1.5px solid var(--border);
  border-radius: var(--r);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  transition: border-color .15s, box-shadow .15s, background .15s;
  position: relative;
}
.track-card.is-loaded {
  border-color: var(--loaded-border);
  background: var(--loaded-bg);
  box-shadow: 0 0 0 3px rgba(47,94,255,.07), var(--shadow-sm);
}
.track-card.is-muted { opacity: .52; }
.track-card.is-solo  { border-color: var(--amber); box-shadow: 0 0 0 3px rgba(245,158,11,.1), var(--shadow-sm); }

/* card header */
.card-header {
  display: flex;
  align-items: center;
  gap: 7px;
  padding: 10px 12px 9px;
  border-bottom: 1px solid var(--border);
  background: var(--surface-2);
}
.track-badge {
  font-family: var(--f-mono);
  font-size: 10px;
  font-weight: 700;
  color: var(--accent);
  background: var(--accent-soft);
  border-radius: 5px;
  padding: 2px 6px;
  flex-shrink: 0;
  letter-spacing: .3px;
}
.track-name {
  font-family: var(--f-mono);
  font-size: 10.5px;
  color: var(--ink-2);
  flex: 1;
  min-width: 0;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.track-clear-btn {
  width: 20px;
  height: 20px;
  border-radius: 50%;
  border: none;
  background: transparent;
  color: var(--ink-3);
  cursor: pointer;
  display: none;
  align-items: center;
  justify-content: center;
  font-size: 13px;
  line-height: 1;
  padding: 0;
  flex-shrink: 0;
  transition: background .1s, color .1s;
}
.track-clear-btn:hover { background: var(--red-soft); color: var(--red); }
.track-card.is-loaded .track-clear-btn { display: flex; }

/* drop zone */
.track-drop-zone {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 22px 12px;
  cursor: pointer;
  gap: 6px;
  transition: background .12s;
  min-height: 90px;
}
.track-drop-zone:hover,
.track-drop-zone.drag-over {
  background: var(--accent-soft);
}
.drop-icon {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: var(--accent-soft);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--accent);
  font-size: 18px;
  font-weight: 300;
  transition: background .12s;
}
.track-drop-zone:hover .drop-icon { background: var(--accent-dim); }
.drop-text {
  font-family: var(--f-mono);
  font-size: 10px;
  color: var(--ink-3);
  letter-spacing: .3px;
}
.track-card.is-loaded .track-drop-zone { display: none; }

/* mini waveform */
.track-wave-canvas {
  display: none;
  width: 100%;
  height: 52px;
  background: linear-gradient(180deg, #f0f3ff 0%, #e8eeff 100%);
}
.track-card.is-loaded .track-wave-canvas { display: block; }

/* track duration meta */
.track-meta-row {
  display: none;
  align-items: center;
  justify-content: space-between;
  padding: 4px 12px;
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}
.track-card.is-loaded .track-meta-row { display: flex; }
.meta-chip {
  font-family: var(--f-mono);
  font-size: 9.5px;
  color: var(--ink-3);
  letter-spacing: .3px;
}

/* controls */
.track-ctrl-list {
  display: flex;
  flex-direction: column;
  gap: 0;
  padding: 10px 12px;
  flex: 1;
}
.ctrl-row {
  display: grid;
  grid-template-columns: 36px 1fr 36px;
  align-items: center;
  gap: 8px;
  padding: 5px 0;
}
.ctrl-row + .ctrl-row {
  border-top: 1px solid var(--border);
}
.ctrl-key {
  font-family: var(--f-mono);
  font-size: 9px;
  letter-spacing: .8px;
  text-transform: uppercase;
  color: var(--ink-3);
  white-space: nowrap;
}
.ctrl-val {
  font-family: var(--f-mono);
  font-size: 10px;
  font-weight: 600;
  color: var(--accent);
  text-align: right;
  white-space: nowrap;
}

/* ── range input — beautiful custom style ── */
.mix-range {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 4px;
  border-radius: 2px;
  outline: none;
  cursor: pointer;
  /* background set dynamically by JS fill logic */
  background: var(--border-mid);
}
.mix-range::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: #fff;
  border: 2px solid var(--accent);
  box-shadow: 0 1px 3px rgba(47,94,255,.22), 0 0 0 0 rgba(47,94,255,0);
  cursor: pointer;
  transition: transform .12s ease, box-shadow .12s ease;
}
.mix-range::-webkit-slider-thumb:hover {
  transform: scale(1.18);
  box-shadow: 0 1px 3px rgba(47,94,255,.3), 0 0 0 5px rgba(47,94,255,.1);
}
.mix-range::-webkit-slider-thumb:active {
  transform: scale(1.05);
  box-shadow: 0 0 0 7px rgba(47,94,255,.13);
}
.mix-range::-moz-range-thumb {
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: #fff;
  border: 2px solid var(--accent);
  box-shadow: 0 1px 3px rgba(47,94,255,.22);
  cursor: pointer;
}
.mix-range::-moz-range-track {
  background: transparent;
  height: 4px;
}
.mix-range:focus { outline: none; }
.mix-range:focus-visible::-webkit-slider-thumb {
  box-shadow: 0 0 0 4px rgba(47,94,255,.2);
}

/* track footer — mute/solo */
.track-footer {
  display: grid;
  grid-template-columns: 1fr 1fr;
  border-top: 1px solid var(--border);
}
.ms-btn {
  font-family: var(--f-mono);
  font-size: 10px;
  font-weight: 700;
  letter-spacing: .5px;
  padding: 8px 4px;
  border: none;
  background: transparent;
  color: var(--ink-3);
  cursor: pointer;
  text-align: center;
  text-transform: uppercase;
  transition: background .1s, color .1s;
}
.ms-btn:first-child { border-right: 1px solid var(--border); border-radius: 0 0 0 calc(var(--r) - 2px); }
.ms-btn:last-child  { border-radius: 0 0 calc(var(--r) - 2px) 0; }
.ms-btn:hover { background: var(--surface-2); color: var(--ink); }
.mute-btn.is-on { background: var(--red-soft);   color: var(--red);   }
.solo-btn.is-on { background: var(--amber-soft);  color: var(--amber); }

/* ── master panel ── */
.master-panel {
  background: var(--surface);
  border: 1.5px solid var(--border);
  border-radius: var(--r);
  box-shadow: var(--shadow-md);
  padding: 20px 24px 22px;
  margin-bottom: 20px;
}
.master-head {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 18px;
}
.master-eyebrow {
  font-family: var(--f-mono);
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 2px;
  text-transform: uppercase;
  color: var(--ink-3);
}
.master-body {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 28px;
  align-items: start;
}
@media (max-width: 680px) { .master-body { grid-template-columns: 1fr; gap: 20px; } }

/* master volume */
.master-vol-group { display: flex; flex-direction: column; gap: 10px; }
.master-ctrl-label {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  font-family: var(--f-mono);
  font-size: 10.5px;
  letter-spacing: .8px;
  text-transform: uppercase;
  color: var(--ink-3);
}
.master-val { color: var(--accent); font-size: 12px; letter-spacing: 0; font-weight: 600; }

.master-range {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 5px;
  border-radius: 3px;
  outline: none;
  cursor: pointer;
  background: var(--border-mid);
}
.master-range::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: #fff;
  border: 2.5px solid var(--accent);
  box-shadow: 0 1px 4px rgba(47,94,255,.25), 0 0 0 0 rgba(47,94,255,0);
  cursor: pointer;
  transition: transform .12s, box-shadow .12s;
}
.master-range::-webkit-slider-thumb:hover {
  transform: scale(1.12);
  box-shadow: 0 1px 4px rgba(47,94,255,.3), 0 0 0 5px rgba(47,94,255,.1);
}
.master-range::-moz-range-thumb {
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: #fff;
  border: 2.5px solid var(--accent);
  cursor: pointer;
}

.vol-presets {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}
.vpre-btn {
  font-family: var(--f-mono);
  font-size: 10.5px;
  font-weight: 600;
  padding: 6px 10px;
  border-radius: var(--r-sm);
  border: 1px solid var(--border-mid);
  background: var(--surface-2);
  color: var(--ink-2);
  cursor: pointer;
  transition: all .1s;
}
.vpre-btn:hover { border-color: var(--accent); color: var(--accent); }
.vpre-btn.active { background: var(--accent); border-color: var(--accent); color: #fff; }

/* master right */
.master-actions {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

/* limiter toggle — custom checkbox */
.limiter-toggle {
  display: flex;
  align-items: center;
  gap: 10px;
  cursor: pointer;
  user-select: none;
}
.limiter-toggle input { display: none; }
.toggle-track {
  width: 36px;
  height: 20px;
  border-radius: 10px;
  background: var(--border-mid);
  flex-shrink: 0;
  position: relative;
  transition: background .18s;
}
.toggle-thumb {
  position: absolute;
  top: 3px;
  left: 3px;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: #fff;
  box-shadow: 0 1px 3px rgba(0,0,0,.2);
  transition: left .18s cubic-bezier(.4,.1,.3,1);
}
.limiter-toggle input:checked ~ .toggle-track { background: var(--accent); }
.limiter-toggle input:checked ~ .toggle-track .toggle-thumb { left: 19px; }
.toggle-label { font-size: 13px; color: var(--ink-2); }

/* export group */
.export-group {
  display: flex;
  gap: 8px;
  align-items: center;
}
.fmt-select {
  font-family: var(--f-mono);
  font-size: 12.5px;
  padding: 10px 12px;
  border: 1.5px solid var(--border-mid);
  border-radius: var(--r-sm);
  background: var(--surface-2);
  color: var(--ink);
  cursor: pointer;
  outline: none;
  flex-shrink: 0;
  transition: border-color .1s;
}
.fmt-select:focus { border-color: var(--accent); }

.mix-btn {
  flex: 1;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-family: var(--f-mono);
  font-size: 12.5px;
  font-weight: 700;
  letter-spacing: .3px;
  padding: 11px 18px;
  border-radius: var(--r-sm);
  border: none;
  background: var(--accent);
  color: #fff;
  cursor: pointer;
  transition: filter .12s, opacity .12s;
  white-space: nowrap;
}
.mix-btn:hover:not(:disabled) { filter: brightness(1.08); }
.mix-btn:disabled { opacity: .38; cursor: not-allowed; }

/* progress */
.progress-wrap { display: flex; flex-direction: column; gap: 8px; }
.progress-bar {
  height: 4px;
  background: var(--border);
  border-radius: 2px;
  overflow: hidden;
  display: none;
}
.progress-bar.show { display: block; }
.progress-bar span {
  display: block;
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--teal), var(--accent));
  border-radius: 2px;
  transition: width .15s ease;
}
.progress-label {
  display: none;
  font-family: var(--f-mono);
  font-size: 11px;
  color: var(--ink-3);
}
.progress-label.show { display: block; }
.status-tag {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 20px;
  font-size: 10.5px;
  text-transform: uppercase;
  letter-spacing: .4px;
}
.status-tag.done  { background: var(--teal-soft); color: var(--teal); }
.status-tag.error { background: var(--red-soft);  color: var(--red);  }

/* ── result panel ── */
.result-panel {
  background: var(--surface);
  border: 1.5px solid var(--border);
  border-radius: var(--r);
  box-shadow: var(--shadow-sm);
  padding: 20px 22px;
  margin-bottom: 20px;
}
.result-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 14px;
  flex-wrap: wrap;
  gap: 10px;
}
.result-badge {
  display: flex;
  align-items: center;
  gap: 7px;
  font-family: var(--f-mono);
  font-size: 11px;
  font-weight: 600;
  color: var(--teal);
  text-transform: uppercase;
  letter-spacing: .5px;
}
.result-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--teal);
}
.dl-btn {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  font-family: var(--f-mono);
  font-size: 12px;
  font-weight: 700;
  padding: 9px 16px;
  border-radius: var(--r-sm);
  background: var(--teal);
  color: #fff;
  text-decoration: none;
  transition: filter .12s;
}
.dl-btn:hover { filter: brightness(1.08); }
.result-wave-wrap {
  border: 1px solid var(--border);
  border-radius: var(--r-sm);
  background: var(--surface-2);
  overflow: hidden;
  margin-bottom: 12px;
}
.result-wave {
  display: block;
  width: 100%;
  height: 80px;
}
#resultAudio {
  width: 100%;
  height: 36px;
  margin-bottom: 12px;
}
.result-info {
  font-family: var(--f-mono);
  font-size: 11.5px;
  color: var(--ink-3);
  line-height: 1.6;
  padding: 12px 14px;
  border-radius: var(--r-sm);
  background: var(--accent-soft);
  color: #1a3299;
}