* { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg: #f6f7fb;
  --panel: #ffffff;
  --line: #e3e6ef;
  --text: #2b2f3a;
  --sub: #7a8199;
  --primary: #5b6cff;
  --primary-dark: #4653e6;
  --ok: #19b273;
  --warn: #e6a23c;
}

body {
  font-family: "Segoe UI", "Microsoft YaHei", system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  height: 100vh;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.topbar {
  display: flex;
  align-items: center;
  gap: 24px;
  background: var(--panel);
  border-bottom: 1px solid var(--line);
  padding: 10px 20px;
  flex: none;
}
.logo { font-size: 18px; font-weight: 700; }
.tabs { display: flex; gap: 6px; }
.tab {
  border: none; background: transparent; padding: 8px 18px;
  font-size: 15px; border-radius: 8px; cursor: pointer; color: var(--sub);
}
.tab.active { background: var(--primary); color: #fff; font-weight: 600; }
.tab:hover:not(.active) { background: #eef0f8; color: var(--text); }

main { flex: 1; overflow: hidden; }
.tab-panel { display: none; height: 100%; }
.tab-panel.active { display: flex; }

/* ---------- 练琴布局 ---------- */
#tab-practice { flex-direction: row; }
.sidebar {
  width: 250px; flex: none; border-right: 1px solid var(--line);
  padding: 14px; overflow-y: auto; background: #fafbfe;
}
.panel { background: var(--panel); border: 1px solid var(--line); border-radius: 12px; padding: 14px; margin-bottom: 14px; }
.panel h3 { font-size: 14px; margin-bottom: 10px; color: var(--sub); }
.library { list-style: none; }
.library li {
  display: flex; justify-content: space-between; align-items: center;
  padding: 8px 10px; border-radius: 8px; cursor: pointer; font-size: 14px;
}
.library li:hover { background: #f0f2fb; }
.library li.active { background: var(--primary); color: #fff; }
.library .del { border: none; background: none; color: var(--sub); cursor: pointer; font-size: 13px; }
.library .del:hover { color: #e5484d; }

.mainarea { flex: 1; display: flex; flex-direction: column; overflow: hidden; padding: 14px 18px; }
.score-title { font-size: 17px; font-weight: 700; margin-bottom: 8px; }
.paper-wrap {
  flex: 1; overflow: auto; background: var(--panel);
  border: 1px solid var(--line); border-radius: 12px; padding: 10px 16px;
}
.paper-wrap.hidden, .hidden { display: none !important; }
.empty-hint {
  flex: 1; display: flex; flex-direction: column; gap: 6px;
  align-items: center; justify-content: center; color: var(--sub);
}
.empty-hint .sub { font-size: 13px; }
.abc-audio { margin-top: 6px; }
.abc-audio .abcjs-midi-tempo { display: none; }

.transport {
  flex: none; display: flex; align-items: center; gap: 10px; flex-wrap: wrap;
  background: var(--panel); border: 1px solid var(--line); border-radius: 12px;
  padding: 10px 14px; margin-top: 10px;
}
.ctl { display: flex; align-items: center; gap: 6px; font-size: 13px; color: var(--sub); }
.ctl.chk { cursor: pointer; }
.ctl input[type="range"] { width: 110px; }
.divider { width: 1px; height: 24px; background: var(--line); }
.ble-status { font-size: 13px; padding: 3px 10px; border-radius: 20px; }
.ble-status.off { background: #f0f1f5; color: var(--sub); }
.ble-status.on { background: #e2f7ee; color: var(--ok); }
.ble-log {
  flex: none; max-height: 90px; overflow-y: auto; margin-top: 8px;
  background: #1d2130; color: #9fe8c1; border-radius: 10px;
  padding: 8px 12px; font-size: 12px; font-family: Consolas, monospace; white-space: pre-wrap;
}

/* ---------- 按钮 ---------- */
.btn {
  border: 1px solid var(--line); background: #fff; color: var(--text);
  border-radius: 9px; padding: 8px 14px; font-size: 14px; cursor: pointer;
}
.btn:hover { border-color: var(--primary); color: var(--primary); }
.btn.primary { background: var(--primary); border-color: var(--primary); color: #fff; font-weight: 600; }
.btn.primary:hover { background: var(--primary-dark); }
.btn:disabled { opacity: 0.45; cursor: not-allowed; }
.btn.wide { width: 100%; }
hr { border: none; border-top: 1px dashed var(--line); margin: 14px 0; }

/* ---------- AI ---------- */
#tab-ai { padding: 16px 20px; gap: 16px; }
.ai-layout { display: flex; gap: 16px; height: 100%; width: 100%; }
.ai-form { width: 300px; flex: none; overflow-y: auto; }
.ai-form label { display: block; font-size: 13px; color: var(--sub); margin-bottom: 10px; }
.ai-form select, .ai-form input[type="text"], .ai-form input[type="password"], .ai-form textarea {
  width: 100%; margin-top: 4px; padding: 7px 10px; border: 1px solid var(--line);
  border-radius: 8px; font-size: 14px; font-family: inherit;
}
.ai-form textarea { resize: vertical; }
.ai-preview { flex: 1; display: flex; flex-direction: column; background: var(--panel); border: 1px solid var(--line); border-radius: 12px; padding: 14px; overflow: hidden; }
.panel-head { display: flex; justify-content: space-between; align-items: center; margin-bottom: 8px; }
.panel-head h3 { color: var(--sub); font-size: 14px; }
.panel-head .btn { margin-left: 8px; }
.ai-status { font-size: 13px; padding: 8px 12px; border-radius: 8px; margin-bottom: 8px; background: #fdeff0; color: #c0392b; }
.ai-status.ok { background: #e2f7ee; color: var(--ok); }
.paper-wrap-scroll { flex: 1; overflow: auto; }

/* ---------- 帮助 ---------- */
#tab-help { overflow-y: auto; display: block; padding: 24px 40px; }
.help { max-width: 780px; }
.help h2 { margin-bottom: 14px; }
.help h3 { margin: 18px 0 8px; color: var(--primary-dark); }
.help ul { padding-left: 22px; line-height: 1.9; }
.help code { background: #eef0f8; padding: 1px 6px; border-radius: 5px; font-size: 13px; }
.help .sub { color: var(--sub); }

/* ---------- toast ---------- */
.toast {
  position: fixed; top: 64px; left: 50%; transform: translateX(-50%);
  background: #2b2f3a; color: #fff; padding: 9px 18px; border-radius: 10px;
  font-size: 14px; z-index: 99; box-shadow: 0 6px 20px rgba(0,0,0,.18);
}
.toast.err { background: #c0392b; }