body {
    font-family: system-ui;
    display: grid;
    place-items: center;
    height: 100vh;
    background: #fafafa;
  }
  
  .d-flex {
    display: flex;
    gap: 2rem;
  }
  
  .caja {
    width: 100px;
    height: 100px;
    border-radius: 8px;
    position: relative;
  }
  
  /* ❌ Provoca reflow: cambia coordenadas de layout */
  .reflow {
    background: royalblue;
    animation: moverLeft 2s infinite alternate;
  }
  
  @keyframes moverLeft {
    from { left: 0; }
    to { left: 200px; }
  }
  
  /* ✅ Más eficiente: usa transform (no recalcula layout) */
  .repaint {
    background: mediumseagreen;
    animation: moverTransform 2s infinite alternate;
  }
  
  @keyframes moverTransform {
    from { transform: translateX(0); }
    to { transform: translateX(200px); }
  }