CSS不会过渡不透明度

Question

我想要做的是在页面加载后使用纯CSS 将弹出窗口延迟几秒钟。我决定最好的方法是转换不透明度，然后使用 transition-delay 将其延迟几秒钟。

我的问题是过渡不起作用并且不会延迟弹出窗口（也不是深色叠加层）。

1. 为什么会这样？我该如何解决？
2. 如果不可能，还有其他方法可以将弹出窗口延迟几秒钟吗？

hr {
  clear: both;
  margin-top: 15px;
  margin-bottom: 15px;
  border: 0;
  border-top: 1px solid #aaaaaa;
}

#css-only-modals {
  position: fixed;
  pointer-events: none;
  left: 0;
  top: 0;
  right: 0;
  bottom: 0;
  z-index: 10000000;
  text-align: center;
  white-space: nowrap;
  height: 100%;
}

#css-only-modals:before {
  content: '';
  display: inline-block;
  height: 100%;
  vertical-align: middle;
  margin-right: -0.25em;
}

.css-only-modal-check {
  pointer-events: auto;
}

.css-only-modal-check:checked~.css-only-modal {
  /* FOR TRANSITION */
  opacity: 1;
  transition: opacity 3s;
  /*NOT WORKING */
  pointer-events: auto;
}

.css-only-modal {
  width: 360px;
  background: #FFF;
  z-index: 1;
  display: inline-block;
  position: relative;
  pointer-events: auto;
  padding: 25px;
  text-align: right;
  border-radius: 4px;
  white-space: normal;
  display: inline-block;
  vertical-align: middle;
  opacity: 0;
  pointer-events: none;
}

.css-only-modal h2 {
  text-align: left;
  color: #1A1A1C;
}

.css-only-modal p {
  text-align: left;
}

.css-only-modal-close {
  position: absolute;
  top: 25px;
  right: 25px;
}

.css-only-modal-check {
  display: none;
}

.css-only-modal-check:checked~#screen-shade {
  /* FOR TRANSITION */
  opacity: 0.5;
  transition: opacity 3s;
  /*NOT WORKING */
  pointer-events: auto;
}

#screen-shade {
  opacity: 0;
  background: #000;
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  bottom: 0;
  pointer-events: none;
  transition: opacity 0.8s;
}

.stripe>.container>p,
.stripe>.container>ul {
  text-align: left;
  padding: 35px;
  margin: 0;
}

#nav-spacer {
  display: block;
  height: 50px;
}

.stripe {
  width: 100%;
  text-align: center;
  overflow: hidden;
}

.css-only-modal-btn {
  background-color: #BD2C15;
  color: white;
  padding: 8px 18px;
  letter-spacing: 0.5px;
}

.css-only-modal-btn:hover {
  color: #BD2C15;
  background-color: transparent;
  outline: 2px solid #BD2C15;
  transition: background-color 0.5s, color 0.5s;
}

<label for="modal1">
  <div id="css-only-modals">
    <input id="modal1" class="css-only-modal-check" type="checkbox" checked/>
    <div class="css-only-modal">
      <label for="modal1" class="css-only-modal-close"><i class="fa fa-times fa-2x"></i></label>
      <h2>Referral</h2>
      <hr />
      <p>Refer a customer, email me and receive a 25% commission. <br> Earn up to 1225$ from a single referral!</p>
      <hr />
      <label for="modal1" class="css-only-modal-btn">NICE!</label>
    </div>
    <div id="screen-shade"></div>
  </div>
</label>

在CSS 中，我创建了两个“FOR TRANSITION”cmets。它们标记了我想要过渡的不透明度。

Answer 1

将过渡效果放在您的初始元素上。

.css-only-modal-check {
    pointer-events: auto;
}


.css-only-modal-check ~ .css-only-modal {
    /* FOR TRANSITION */
    transition: opacity 3s; 
}

.css-only-modal-check:checked ~ .css-only-modal {
    opacity: 1;
    pointer-events: auto;
}

.css-only-modal {
    width: 360px;
    background: #FFF;
    z-index: 1;
    display: inline-block;
    position: relative;
    pointer-events: auto;
    padding: 25px;
    text-align: right;
    border-radius: 4px;
    white-space: normal;
    display: inline-block;
    vertical-align: middle;
    opacity: 0;
    pointer-events: none;
}

Answer 2

还要确保始终设置过渡，仅在 ~checked 时将不透明度更改为 0。

transition-delay 也必须在转换之下。 这是完整的修改代码

.css-only-modal-check {
    pointer-events: auto;
}


.css-only-modal-check ~ .css-only-modal {
    /* FOR TRANSITION */
    transition: opacity 3s; 
}

.css-only-modal-check:checked ~ .css-only-modal {
    opacity: 0;
    pointer-events: auto;
}

.css-only-modal {
    width: 360px;
    background: #FFF;
    z-index: 1;
    display: inline-block;
    position: relative;
    pointer-events: auto;
    padding: 25px;
    text-align: right;
    border-radius: 4px;
    white-space: normal;
    display: inline-block;
    vertical-align: middle;
    /*opacity: 0;*/
    transition: opacity 3s; 
    transition-delay:2s;
    pointer-events: none;
}