.required {
    box-shadow: 4px 4px 20px rgba(200, 0, 0, 0.85);
  }
  
  /**
   * style input elements that have a required
   * attribute and a focus state
   */
.required:focus {
    border: 1px solid red;
    outline: none;
  }
  
  /**
   * style input elements that have a required
   * attribute and a hover state
   */
.required:hover {
    opacity: 1;
  }