:root {
  --bg: #f6f7f9;
  --panel: #ffffff;
  --text: #1f2937;
  --muted: #6b7280;
  --border: #d1d5db;
  --accent: #0f766e;
  --accent-hover: #0b5f59;
  --ghost: #eef2f7;
}

body.dark {
  --bg: #0f1117;
  --panel: #181c25;
  --text: #e5e7eb;
  --muted: #9ca3af;
  --border: #2a3140;
  --accent: #1da39a;
  --accent-hover: #16857d;
  --ghost: #232a37;
}

* { box-sizing: border-box; }

html, body { margin: 0; }

body {
  font-family: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  color: var(--text);
  background: linear-gradient(180deg, var(--bg) 0%, #f8fafc 100%);
  -webkit-font-smoothing: antialiased;
  -webkit-tap-highlight-color: transparent;
  padding-left: env(safe-area-inset-left);
  padding-right: env(safe-area-inset-right);
}

body.dark { background: linear-gradient(180deg, #0d1117 0%, #121826 100%); }

.container {
  max-width: 860px;
  margin: 24px auto;
  padding: 0 14px calc(24px + env(safe-area-inset-bottom));
}

.topbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
}

h1 { margin: 0; font-size: 1.85rem; }
.subtitle { margin-top: 8px; color: var(--muted); }
h2 { margin: 0 0 12px; font-size: 1.08rem; }

.tabs {
  margin-top: 14px;
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 8px;
}

.tab-btn {
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--ghost);
  color: var(--text);
  min-height: 44px;
  padding: 10px;
}

.tab-btn.active {
  background: var(--accent);
  color: #fff;
  border-color: transparent;
}

.tab-panel { display: none; }
.tab-panel.active { display: block; }

.card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 16px;
  margin-top: 12px;
}

label {
  display: block;
  margin: 10px 0 6px;
  font-weight: 600;
}

input[type="number"],
input[type="range"] { width: 100%; }

input[type="number"] {
  min-height: 44px;
  padding: 10px;
  border-radius: 8px;
  border: 1px solid var(--border);
  font-size: 16px;
  background: transparent;
  color: var(--text);
}

.freq-line {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 8px;
}

.freq-inputs { display: grid; gap: 8px; }
.freq-inputs.two-col { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 10px; }

.step-buttons,
.buttons,
.preset-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.preset-row { margin-top: 10px; align-items: center; }

button {
  border: none;
  border-radius: 8px;
  padding: 10px 14px;
  min-height: 44px;
  background: var(--accent);
  color: #fff;
  font-size: 0.96rem;
  cursor: pointer;
  touch-action: manipulation;
}

button:hover { background: var(--accent-hover); }

.ghost-btn,
.preset-btn {
  background: var(--ghost);
  color: var(--text);
  border: 1px solid var(--border);
}

.ghost-btn.active { background: var(--accent); color: #fff; border-color: transparent; }

.info p { margin: 10px 0; color: var(--muted); }
.tips ul { margin: 0; padding-left: 20px; color: var(--muted); }

.status {
  margin: 14px 2px 0;
  font-weight: 600;
  color: var(--muted);
}

@media (max-width: 760px) {
  .tabs {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    position: sticky;
    top: 0;
    z-index: 30;
    background: var(--bg);
    padding-top: 6px;
    padding-bottom: 6px;
  }
}

@media (max-width: 640px) {
  h1 { font-size: 1.55rem; }
  .topbar { align-items: flex-start; flex-direction: column; }
  .freq-inputs.two-col { grid-template-columns: 1fr; }
  .container { margin-top: 12px; }
}