:root {
  --bg: #f5f7fb;
  --panel: #ffffff;
  --panel-2: #eef3fb;
  --text: #151922;
  --muted: #667089;
  --line: #d7deea;
  --accent: #059669;
  --accent-soft: rgba(5,150,105,.10);
  --shadow: 0 20px 50px rgba(17,24,39,.08);
  --play: #7c3aed;
}
* { box-sizing: border-box; }
body { margin-top: 70px; padding: 0; background: var(--bg); color: var(--text); font-family: -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Noto Sans KR",sans-serif; }
button,select { font: inherit; cursor: pointer; }
h2,h3,ol,p { margin-top: 0; }

.spk-app { max-width: 100%; padding: 24px 0 60px; }

/* Header */
.spk-header {
  background: var(--panel); border: 1px solid var(--line); border-radius: 22px;
  box-shadow: var(--shadow); padding: 28px;
  display: flex; justify-content: space-between; align-items: flex-start; gap: 20px;
}
.spk-title { margin: 0 0 8px; font-size: 34px; line-height: 1.15; }
.spk-sub { margin: 0; color: var(--muted); }
.spk-header-acts { display: flex; gap: 10px; flex-shrink: 0; justify-content: flex-end; padding: 8px 0 4px; }

/* Buttons */
.spk-btn {
  appearance: none; border-radius: 14px; padding: 12px 18px;
  font-weight: 700; font-size: 14px; border: 1px solid var(--line);
  background: var(--panel-2); color: var(--text); white-space: nowrap;
}
.spk-ghost   { background: var(--panel-2); color: var(--text); }
.spk-btn:hover { opacity: .88; }

/* Strip */
.spk-strip {
  display: grid; grid-template-columns: repeat(6,minmax(0,1fr)); gap: 12px;
  margin-top: 16px; background: var(--panel); border: 1px solid var(--line);
  border-radius: 22px; box-shadow: var(--shadow); padding: 16px;
}
.spk-metric { background: var(--panel-2); border: 1px solid var(--line); border-radius: 18px; padding: 14px; }
.spk-metric span { display: block; font-size: 12px; color: var(--muted); margin-bottom: 8px; }
.spk-metric strong { font-size: 20px; }

/* Main */
.spk-main { margin-top: 16px; display: grid; gap: 16px; }
.spk-panel { background: var(--panel); border: 1px solid var(--line); border-radius: 22px; box-shadow: var(--shadow); padding: 24px; }
.spk-panel-head { display: flex; justify-content: space-between; align-items: flex-start; gap: 16px; margin-bottom: 20px; }
.spk-panel-head h2 { margin: 0 0 6px; font-size: 22px; }
.spk-panel-head p { margin: 0; color: var(--muted); }

/* Device */
.spk-device-row { display: flex; align-items: center; gap: 14px; flex-wrap: wrap; }
.spk-select { flex: 1; min-width: 240px; border: 1px solid var(--line); background: var(--panel-2); color: var(--text); border-radius: 14px; padding: 14px 16px; font-size: 15px; }
.spk-device-note { font-size: 13px; color: var(--muted); }

/* Control grid */
.spk-control-grid { display: grid; grid-template-columns: 1fr 1fr auto; gap: 20px; align-items: end; }
.spk-control-item { display: grid; gap: 10px; }
.spk-control-item--full { justify-self: stretch; }
.spk-control-label { display: flex; justify-content: space-between; font-weight: 700; font-size: 14px; }
.spk-control-label span { color: var(--muted); }
.spk-range {
  -webkit-appearance: none; width: 100%; height: 6px;
  border-radius: 3px; background: var(--line); outline: none; cursor: pointer;
}
.spk-range::-webkit-slider-thumb {
  -webkit-appearance: none; width: 20px; height: 20px;
  border-radius: 50%; background: var(--play); box-shadow: 0 2px 8px rgba(124,58,237,.35); cursor: pointer;
}
.spk-range--freq::-webkit-slider-thumb { background: var(--accent); box-shadow: 0 2px 8px rgba(5,150,105,.35); }
.spk-play-btn {
  width: 100%; padding: 16px; border-radius: 16px;
  background: var(--play); color: #fff; border: none;
  font-weight: 700; font-size: 16px;
}
.spk-play-btn:hover { opacity: .88; }
.spk-play-btn.is-playing { background: #5b21b6; }

/* Channel grid */
.spk-channel-grid { display: grid; grid-template-columns: repeat(3,1fr); gap: 16px; }
.spk-channel-card {
  background: var(--panel-2); border: 1px solid var(--line); border-radius: 20px;
  padding: 24px; text-align: center; display: grid; gap: 10px; align-content: start;
}
.spk-channel-card.is-playing { border-color: var(--play); background: rgba(124,58,237,.06); }
.spk-channel-icon { font-size: 28px; }
.spk-channel-card h3 { margin: 0; font-size: 18px; }
.spk-channel-card p  { margin: 0; color: var(--muted); font-size: 14px; }
.spk-test-btn {
  padding: 14px; border-radius: 14px;
  background: var(--play); color: #fff; border: none;
  font-weight: 700; font-size: 14px; margin-top: 8px;
}
.spk-test-btn:hover { opacity: .88; }
.spk-test-btn.is-playing { background: #5b21b6; }

/* Advanced */
.spk-adv-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.spk-adv-card {
  background: var(--panel-2); border: 1px solid var(--line); border-radius: 20px;
  padding: 24px; display: grid; gap: 10px; align-content: start;
}
.spk-adv-card.is-playing { border-color: var(--accent); background: rgba(5,150,105,.06); }
.spk-adv-icon { font-size: 28px; }
.spk-adv-card h3 { margin: 0; font-size: 18px; }
.spk-adv-card p  { margin: 0; color: var(--muted); font-size: 14px; }
.spk-sweep-progress { height: 6px; background: var(--line); border-radius: 3px; overflow: hidden; }
.spk-sweep-progress div { height: 100%; background: var(--accent); width: 0; border-radius: 3px; transition: width .1s; }
.spk-binaural-viz {
  height: 80px; position: relative; border-radius: 40px;
  background: var(--line); overflow: visible; display: flex; align-items: center;
}
.spk-binaural-dot {
  position: absolute; width: 20px; height: 20px;
  background: var(--accent); border-radius: 50%;
  top: 50%; transform: translateY(-50%); left: 50%;
  transition: left .08s;
}

/* Samples grid */
.spk-samples-grid { display: grid; grid-template-columns: repeat(4,1fr); gap: 12px; }
.spk-sample-btn {
  background: var(--panel-2); border: 1px solid var(--line); border-radius: 18px;
  padding: 18px 14px; text-align: center; display: grid; gap: 6px;
  transition: border-color .15s, background .15s;
}
.spk-sample-btn:hover { border-color: var(--play); }
.spk-sample-btn.is-playing { border-color: var(--play); background: rgba(124,58,237,.08); }
.spk-sample-icon { font-size: 22px; }
.spk-sample-btn strong { font-size: 15px; display: block; }
.spk-sample-btn small { color: var(--muted); font-size: 12px; }

/* Guide */
.spk-guide-list { padding-left: 20px; color: var(--muted); line-height: 1.8; display: grid; gap: 8px; }
.spk-guide-list strong { color: var(--text); }

/* Responsive */
@media (max-width: 980px) {
  .spk-strip { grid-template-columns: repeat(3,1fr); }
  .spk-control-grid { grid-template-columns: 1fr; }
  .spk-control-item--full { justify-self: auto; }
  .spk-samples-grid { grid-template-columns: repeat(2,1fr); }
  .spk-adv-grid { grid-template-columns: 1fr; }
}
@media (max-width: 640px) {
  .spk-strip { grid-template-columns: repeat(2,1fr); }
  .spk-channel-grid { grid-template-columns: 1fr; }
  .spk-samples-grid { grid-template-columns: repeat(2,1fr); }
  .spk-panel-head { flex-direction: column; }
  .spk-title { font-size: 26px; }
}