出現的問題：
我們想要的效果：
結構：
<body>
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<div class="box">
<div class="box_bg"></div>
<div class="box_bubble">
<h2>hello!muzidigbig</h2>
<input type="text">
</div>
</div>
</body>
出現問題的樣式：
<style>
.box {
position: fixed;
left: 0;
top: 0;
height: 100%;
width: 100%;
text-align: center;
}
.box_bg {
position: fixed;
left: 0;
top: 0;
z-index: -1;
width: 100%;
height: 100%;
background-color: #000;
filter: alpha(opacity=30);
opacity: .3;
}
.box_bubble {
background: #fff;
width: 400px;
padding: 50px;
text-align: left;
border: 2px solid pink;
/* 這種定位方式會使input表單設有border的邊框線加粗 */
position: absolute;
left: 50%;
top: 50%;
transform: translate(-50%, -50%);
}
input {
border: 1px solid #666;
}
</style>
我們想要的效果的樣式：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<style>
.box {
position: fixed;
left: 0;
top: 0;
height: 100%;
width: 100%;
text-align: center;
}
.box::before {
content: "";
height: 100%;
display: inline-block;
vertical-align: middle;
}
.box_bg {
position: fixed;
left: 0;
top: 0;
z-index: -1;
width: 100%;
height: 100%;
background-color: #000;
filter: alpha(opacity=30);
opacity: .3;
}
.box_bubble {
background: #fff;
width: 400px;
padding: 50px;
text-align: left;
border: 2px solid pink;
position: static;
top: auto;
left: auto;
transform: none;
margin-left: 0;
display: inline-block;
vertical-align: middle;
}
input {
border: 1px solid #666;
}
</style>
</head>
<body>
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<div class="box">
<div class="box_bg"></div>
<div class="box_bubble">
<h2>hello!muzidigbig</h2>
<input type="text">
</div>
</div>
</body>
</html>
這裏我也有疑問 就是不知道下面這塊代碼表達的原理是什麼？
.box::before {
content: "";
height: 100%;
display: inline-block;
vertical-align: middle;
}