:root {
  --bg: #eef5ff;
  --card: #ffffff;
  --text: #10233f;
  --muted: #5d6f89;
  --accent: #1677ff;
  --danger: #df4d4d;
  --ok: #21b36a;
  --border: #d7e3f5;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: radial-gradient(circle at 0% 0%, #dcecff, var(--bg) 55%, #f8fbff);
  color: var(--text);
  min-height: 100vh;
}

.app {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 20px;
}

.card {
  width: min(760px, 100%);
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 24px;
  box-shadow: 0 16px 40px rgba(17, 61, 130, 0.12);
}

h1 {
  margin: 0 0 10px;
  font-size: clamp(1.4rem, 4vw, 2rem);
}

.subtitle {
  margin: 0 0 18px;
  color: var(--muted);
  line-height: 1.5;
}

.controls {
  display: flex;
  gap: 10px;
  margin-bottom: 16px;
}

button {
  border: 0;
  border-radius: 12px;
  padding: 10px 16px;
  cursor: pointer;
  font-size: 1rem;
}

button:disabled {
  opacity: 0.55;
  cursor: not-allowed;
}

button.primary {
  background: var(--accent);
  color: #ffffff;
  font-weight: 700;
}

#stopBtn {
  background: #fff5f5;
  color: #a02727;
  border: 1px solid #f3bcbc;
}

.gain-wrap {
  display: grid;
  grid-template-columns: 1fr;
  gap: 8px;
  margin-bottom: 16px;
}

.device-wrap {
  margin-bottom: 16px;
}

.device-wrap label {
  display: block;
  margin-bottom: 8px;
  color: var(--muted);
}

.device-row {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 8px;
}

#micSelect {
  width: 100%;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: #ffffff;
  color: var(--text);
  padding: 10px;
}

#refreshDevicesBtn {
  border: 1px solid var(--border);
  background: #f6f9ff;
  color: var(--text);
}

.device-tip {
  margin: 8px 0 0;
  color: var(--muted);
  font-size: 0.92rem;
}

#gainRange {
  width: 100%;
}

#gainValue {
  color: var(--muted);
  font-variant-numeric: tabular-nums;
}

.meter-wrap {
  margin-bottom: 16px;
}

.meter-label {
  margin-bottom: 8px;
  color: var(--muted);
}

.meter-bg {
  height: 14px;
  border-radius: 999px;
  overflow: hidden;
  background: #e7eefc;
}

.meter-bar {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--ok), #ffd86b, var(--danger));
  transition: width 0.08s linear;
}

.status {
  padding: 10px 12px;
  border-radius: 10px;
  background: #f2f7ff;
  border: 1px solid var(--border);
  margin: 0 0 14px;
}

details {
  border-top: 1px solid var(--border);
  padding-top: 12px;
  color: var(--muted);
}

details ol {
  margin: 8px 0;
  padding-left: 20px;
}

.tip {
  margin: 0;
  font-size: 0.95rem;
}

.support {
  margin: 14px 0 0;
  color: #436088;
  font-size: 0.92rem;
}

@media (max-width: 640px) {
  .device-row {
    grid-template-columns: 1fr;
  }
}