html学习3-CSS补充

position

fixed：把标签固定在页面的某处

例子：使用fixed制作“回到顶部”按钮

<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <title></title>

</head>

<body>

    <div onclick="GoTop();" style="width:50px;height:50px;background-color:black;color:white;

    position:fixed;bottom:20px;right:20px">

        返回顶部

    </div>

    <div style="height:5000px;background-color:#dddddd">

        ddfdfdadfdf

    </div>

    <script>

        function GoTop(){

            document.documentElement.scrollTop = 0;

            console.log(document.documentElement.scrollTop)

        }

    </script>

</body>

</html>

例子2：固定页面头部

<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <title></title>

    <style>

        .pg-header{

            height:48px;

            background-color:black;

            color:#dddddd;

            position:fixed;

            top:0;

            right:0;

            left:0;

        }

        .pg-body{

            background-color:#dddddd;

            height:5000px;

            margin-top:50px;

        }

    </style>

</head>

<body>

    <div class="pg-header">头部</div>

    <div class="pg-body">内容</div>

</body>

</html>

absolute：把标签固定在页面的某处，位置是绝对固定的

relative：通常和absolute一起用

<div style='position:relative;'>
   <div style='position:absolut;top:0,right:0;'></div>
<div/>

例子：

<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <title></title>

</head>

<body>

    <div style="width:50px;height:50px;

    background-color:black;

    position:absolute;

    right:0;

    bottom:0;">

    </div>

    <div style="margin:0 auto;position:relative;width:500px;height:200px;border:1px solid red;">

        <div style="position:absolute;left:0;bottom:0;width:50px;height:50px;background-color:black;"></div>

    </div>

    <div style="margin:0 auto;position:relative;width:500px;height:200px;border:1px solid red;">

        <div style="position:absolute;right:0;bottom:0;width:50px;height:50px;background-color:blue;"></div>

    </div>

    <div style="margin:0 auto;position:relative;width:500px;height:200px;border:1px solid red;">

        <div style="position:absolute;right:0;top:0;width:50px;height:50px;background-color:blue;"></div>

    </div>

    <div style="height:5000px;background-color:#dddddd;">

        ddfdfdadfdf

    </div>

</body>

</html>

页面分层显示：

z-index

opacity 透明值：0-1

<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <title></title>

</head>

<body>

    <div style="display:none;z-index:10;

    position:fixed;background-color:white;

    height:100px;

    width:500px;

    top:50%;

    left:50%;

    margin-left:-250px;margin-top:-200px;

    ">

        <input type="text">

        <input type="text">

        <input type="text">

    </div>

    <div style="display:none;z-index:9;position:fixed;background-color:#dddddd;

    top:0;

    bottom:0;

    left:0;

    right:0;

    opacity:0.5;

    "></div>

    <div style="height:5000px;background-color:green;">

        ddfdfdadfdf

    </div>

</body>

</html>

overflow

例子：

<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <title></title>

</head>

<body>

    <div style="height:200px;width:300px;overflow:hidden;">

        <img src="IMG_1980.JPG">

    </div>

    <p></p>

    <div style="height:200px;width:300px;overflow:auto;">

        <img src="IMG_1980.JPG">

    </div>

</body>

</html>

hover

鼠标移动到标签时，属性才生效

<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <title></title>

    <style>

        .pg-header{

            position:fixed;

            right:0;

            left:0;

            top:0;

            height:48px;

            background-color:#2459a2;

            line-height:48px;

            }

        .pg-body{

            margin-top:50px;

            }

        .w{

            width:980px;

            margin:0 auto;

            }

        .pg-header .menu{

            display:inline-block;

            padding:0 10px 0 10px;

            color:white;

            }

        .pg-header .menu:hover{

            background-color:blue;

            }

    </style>

</head>

<body>

    <div class="pg-header">

        <div class="w">

            <a class="logo">LOGO</a>

            <a class="menu">全部</a>

            <a class="menu">42区</a>

            <a class="menu">段子</a>

            <a class="menu">1024</a>

        </div>

    </div>

    <div class="pg-body">

        <div class="w">g</div>

    </div>

</body>

</html>

background-color　　背景颜色

background-image:url('xxx.gif')#默认。div大，图片重复放

background-repeat:no-repeat/repeat-x/repeat-y 图片重复加载

background-position:10px 10px/position-x/position-y 移动背景图片

<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <title></title>

</head>

<body>

    <span style="background-image:url('微笑.gif');height:20px;width:20px;display:inline-block;"></span>

    <div style="height:35px;width:400px;position:relative;">

        <input type="text" style="height:35px;width:370px;padding-right:30px" />

        <span style="position:absolute;right:0;top:10px;background-image:url('微笑.gif');height:25px;width:25px;display:inline-block;"></span>

    </div>

    <div style="width:200px;height:200px;border:1px solid red;

     background-image:url('土拨鼠.gif');

     background-repeat:no-repeat;

     background-position-x:10px;

     background-position-y:10px"></div>

</body>

</html>

结束

巴特西

html学习3-CSS补充

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