模态框实例

HTML代码如下：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>模态框</title>
    <link rel="stylesheet" href="modal.css">
    <script src="modal.js"></script>
</head>
<body>
    <header>
        <h2 class="title">上草一方的博客</h2>
        <button onclick="showModal()">登录</button>
    </header>
    <!-- 模态框 -->
    <div class="modal">
        <!-- 1.半透明的遮罩 -->
        <div class="modal-bg" onclick="closeModal()"></div>
        <!-- 2.弹层表单 -->
        <form action="" class="modal-form">
            <fieldset style="display: grid;gap: 1em;">
                <legend>用户登录</legend>
                <input type="email" name="email" placeholder="user@email.com">
                <input type="password" name="pwd" placeholder="不少于8位">
                <button>登录</button>
            </fieldset>
        </form>
    </div>
</body>
</html>

CSS代码如下：

/* 初始化 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
/* 头部样式 */
header {
    background-color: lightseagreen;
    padding: 0.5em 1em;
    display: flex;
}
header .title{
    font-weight: lighter;
    font-style: italic;
    color: white;
    letter-spacing: 2px;
    text-shadow: 1px 1px 1px #555;
}
/* 登录按钮 */
header button{
    margin-left: auto;
    width: 5em;
    border: none;
    border-radius: 0.5em;
}
header button:hover{
    cursor: pointer;
    background-color:hotpink;
    color: #fff;
    box-shadow: 2px 2px 4px white;
    transition: 0.3s;
}
/* 模态框 */
.modal .modal-form fieldset{
    height: 17.5em;
    background-color: lightcyan;
    border: none;
    padding: 2em 3em;
    box-shadow: 0 0 5px #888;
}
.modal .modal-form fieldset legend{
    padding: 7px 1.5em;
    background-color:aqua;
    color: #fff;
    border-radius: 5px;
}
.modal .modal-form fieldset input{
    height: 2.5em;
    padding-left: 1em;
    border: 1px solid #ddd;
    outline: none;
    font-size: 14px;
}
.modal .modal-form fieldset input:focus{
    box-shadow: 2px 2px 8px #888;
    border: none;
}
.modal .modal-form fieldset button{
    background-color: lightseagreen;
    color: #fff;
    border: none;
    height: 3em;
    font-size: 16px;
    height: 2.5em;
    border-radius: 5px;
}
.modal .modal-form fieldset button:hover{
    background-color: hotpink;
    cursor: pointer;
    box-shadow: 2px 2px 8px gray;
}
/* 定位 */
.modal .modal-form{
    position: fixed;
    top: 10em;
    left: 30em;
    right: 30em;
}
/* 遮罩 */
.modal .modal-bg{
    position: fixed;
    /* 坐标全部清零，请定位到四个顶点 */
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color:rgba(0,0,0,0.5);
}
.modal{
    display: none;
}

运行效果图如下：