* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', sans-serif;
  }
  
  body {
    background: #0f1720;
    color: #e5e7eb;
  }
  
  /* HEADER */
  .header {
    text-align: center;
    padding: 20px;
  }
  
  .header h1 {
    color: #22c55e;
    font-size: 1.8rem;
  }
  
  .header p {
    opacity: 0.7;
  }
  
  /* LAYOUT */
  .container {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 20px;
    padding: 20px;
  }
  
  /* SIMULATOR */
  .simulator {
    background: #111827;
    border-radius: 16px;
    padding: 10px;
    box-shadow: 0 0 20px rgba(34,197,94,0.2);
  }
  
  #reactorCanvas {
    width: 100%;
    height: 400px;
    border-radius: 12px;
    display: block;
  }

  .energy-chart {
    background: #111827;
    border-radius: 16px;
    padding: 12px 14px 14px;
    box-shadow: 0 0 15px rgba(34, 197, 94, 0.12);
    flex: 0 0 auto;
    min-width: 0;
  }

  .chart-title {
    font-size: 0.95rem;
    color: #4ade80;
    font-weight: 600;
    margin-bottom: 2px;
  }

  #chartCanvas {
    width: 100%;
    height: 160px;
    margin-top: 10px;
    border-radius: 12px;
    display: block;
    background: rgba(15, 23, 32, 0.95);
    border: 1px solid rgba(74, 222, 128, 0.18);
  }

  .sim-hints {
    margin-top: 14px;
    padding: 12px 14px;
    border-radius: 12px;
    background: rgba(15, 23, 32, 0.85);
    border: 1px solid rgba(74, 222, 128, 0.2);
    font-size: 0.82rem;
    line-height: 1.55;
    color: rgba(229, 231, 235, 0.82);
  }

  .sim-hints p + p {
    margin-top: 0.45em;
  }

  .meltdown-explain {
    margin-top: 12px;
    padding: 14px 16px;
    border-radius: 12px;
    background: linear-gradient(135deg, rgba(60, 20, 25, 0.95), rgba(25, 15, 20, 0.98));
    border: 1px solid rgba(248, 113, 113, 0.45);
    box-shadow: 0 0 24px rgba(220, 38, 38, 0.2);
  }

  .meltdown-explain h4 {
    color: #fca5a5;
    font-size: 0.95rem;
    margin-bottom: 0.5em;
  }

  .meltdown-explain p {
    font-size: 0.82rem;
    line-height: 1.55;
    color: rgba(254, 226, 226, 0.9);
  }

  .meltdown-explain[hidden] {
    display: none !important;
  }

  .reset-btn {
    width: 100%;
    padding: 10px 14px;
    border-radius: 10px;
    border: 1px solid rgba(74, 222, 128, 0.5);
    background: rgba(22, 101, 52, 0.35);
    color: #bbf7d0;
    font-size: 0.9rem;
    cursor: pointer;
    transition: background 0.15s, border-color 0.15s;
  }

  .reset-btn:hover {
    background: rgba(34, 197, 94, 0.25);
    border-color: rgba(74, 222, 128, 0.85);
  }

  .reset-btn:focus-visible {
    outline: 2px solid #4ade80;
    outline-offset: 2px;
  }

  .reset-btn[hidden] {
    display: none !important;
  }
  
  /* CONTROLS */
  .controls {
    display: flex;
    flex-direction: column;
    gap: 15px;
  }
  
  .control {
    background: #111827;
    padding: 12px;
    border-radius: 12px;
  }
  
  .control label {
    font-size: 0.9rem;
    margin-bottom: 5px;
    display: block;
  }
  
  input[type="range"] {
    width: 100%;
    accent-color: #22c55e;
  }
  
  /* STATS */
  .stats {
    grid-column: span 2;
    display: flex;
    gap: 15px;
  }
  
  .card {
    flex: 1;
    background: #111827;
    padding: 15px;
    border-radius: 12px;
    text-align: center;
    box-shadow: 0 0 15px rgba(34,197,94,0.15);
  }
  
  .card h3 {
    color: #4ade80;
    font-size: 1rem;
  }
  
  .card p {
    font-size: 1.4rem;
    margin-top: 5px;
  }
  
  /* RESPONSIVE 🔥 */
  @media (max-width: 900px) {
    .container {
      grid-template-columns: 1fr;
    }
  
    .stats {
      flex-direction: column;
    }
  
    #reactorCanvas {
      height: 250px;
    }
  }