js alert样式修改

<div id="customAlert" class="modal">
  <div class="modal-content">
    <span class="close-button">&times;</span>
    <p>This is a custom alert!</p>
    <button id="alertOk">OK</button>
  </div>
</div>

.modal {
  display: none; /* Hidden by default */
  position: fixed; /* Stay in place */
  z-index: 1; /* Sit on top */
  left: 0;
  top: 0;
  width: 100%; /* Full width */
  height: 100%; /* Full height */
  overflow: auto; /* Enable scroll if needed */
  background-color: rgb(0,0,0); /* Fallback color */
  background-color: rgba(0,0,0,0.4); /* Black w/ opacity */
}

.modal-content {
  background-color: #fefefe;
  margin: 15% auto; /* 15% from the top and centered */
  padding: 20px;
  border: 1px solid #888;
  width: 80%; /* Could be more or less, depending on screen size */
}

.close-button {
  color: #aaa;
  float: right;
  font-size: 28px;
  font-weight: bold;
}

.close-button:hover,
.close-button:focus {
  color: black;
  text-decoration: none;
  cursor: pointer;
}

function customAlert(message) {
  const modal = document.getElementById("customAlert");
  const span = document.getElementsByClassName("close-button")[0];
  const okButton = document.getElementById("alertOk");

  document.querySelector(".modal-content p").innerText = message;
  modal.style.display = "block";

  span.onclick = function() {
    modal.style.display = "none";
  }

  okButton.onclick = function() {
    modal.style.display = "none";
  }

  window.onclick = function(event) {
    if (event.target == modal) {
      modal.style.display = "none";
    }
  }
}

// Usage
customAlert("This is a custom alert!");