custom_nodes/ComfyUI-N-Nodes/js/styles.css

textarea[placeholder="positive_prompt"] {
    border: 1px solid #64d509;
 

  }
  textarea[placeholder="positive_prompt"]:focus-visible {
    border: 1px solid #72eb0f;

  }


textarea[placeholder="negative_prompt"] {
  border: 1px solid #a94442;
  border-color: #a94442; 
}

textarea[placeholder="negative_prompt"]:focus-visible {
  border: 1px solid #de5755;
  border-color: #de5755; 
}