body {
      background-color: #0f1117;
      color: #e2e8f0;
      font-family: 'Inter', system-ui, sans-serif;
      overflow: hidden;
      height: 100vh;
      display: flex;
      flex-direction: column;
    }
    .key {
      transition: transform 0.05s, background-color 0.1s;
      cursor: pointer;
      user-select: none;
    }
    .white-key {
      background: linear-gradient(to bottom, #eee, #fff);
      height: 200px;
      width: 50px;
      border: 1px solid #ccc;
      border-radius: 0 0 5px 5px;
      z-index: 10;
    }
    .white-key.active {
      background: #4ade80;
      transform: translateY(2px);
    }
    .black-key {
      background: #1e293b;
      height: 120px;
      width: 34px;
      margin-left: -17px;
      margin-right: -17px;
      z-index: 20;
      border-radius: 0 0 3px 3px;
      border: 1px solid #000;
    }
    .black-key.active {
      background: #22c55e;
      transform: translateY(2px);
    }
    .recording-dot {
      animation: blink 1s infinite;
    }
    @keyframes blink {
      0%, 100% { opacity: 1; }
      50% { opacity: 0.3; }
    }

    /* Flow Visualizer Styles */
    #flow-container {
      position: absolute;
      bottom: 210px; /* Piano height */
      left: 0;
      right: 0;
      top: 0;
      pointer-events: none;
      overflow: hidden;
      z-index: 5;
    }
    .note-bar {
      position: absolute;
      bottom: 0;
      border-top-left-radius: 4px;
      border-top-right-radius: 4px;
      animation: flowUp linear forwards;
      filter: blur(2px);
      box-shadow: 0 0 15px currentColor;
    }
    @keyframes flowUp {
      from { transform: translateY(0); opacity: 0.8; }
      to { transform: translateY(-100vh); opacity: 0; }
    }