CSS 页面加载动画

Question

为什么以下代码在页面加载时没有动画？

#error {
    opacity: 0 text-align: center;
    background-color: rgba(255, 0, 0, 0.4);
    border-radius: 10px;
    border: 4px solid rgba(255, 0, 0, 0.4);
    line-height: 1.5;
    -webkit-background-clip: padding-box; /* for Safari */
    background-clip: padding-box;
}
.animate {
    opacity: 1;
    transition: opacity 0.4s ease-in;
    -ms-transition: opacity 0.4s ease-in;
    -moz-transition: opacity 0.4s ease-in;
    -webkit-transition: opacity 0.4s ease-in;
}

<div id="error" class="animate">This is an error message!</div>

Answer 1

如果要有动画，则不能同时应用两种样式。

为此，您可以使用 JavaScript 在页面加载后应用 opacity 属性。

window.onload = function() {
    document.getElementById("error").style.opacity = 1;
}

#error {
    opacity: 0;
    text-align: center;
    background-color: rgba(255, 0, 0, 0.4);
    border-radius: 10px;
    border: 4px solid rgba(255, 0, 0, 0.4);
    line-height:1.5;
    -webkit-background-clip: padding-box; /* for Safari */
    background-clip: padding-box;
    transition: opacity 0.4s ease-in;
    -ms-transition: opacity 0.4s ease-in;
    -moz-transition: opacity 0.4s ease-in;
    -webkit-transition: opacity 0.4s ease-in;
}

<div id="error">This is an error message!</div>

CSS 页面加载动画

CSS animation on page load

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css

css-animations