兼容到ie7的背景图片

记录一次img替换background：url（" "）;来做网页背景的例子：

网页自适应兼容到ie7;

    
    
    


    
    

        
        

            

                
                

                    
                    *****
                    
互联网信贷管理平台
                
            

            
            
            

                

                    
                
                

                    
                    
                    
请输入用户名
                
                

                    
                    
                    
请输入密码
                
                

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js

$(".name input").focus(function(){
  $(".name p").text('');
});
$(".password input").focus(function(){
  $(".password p").text('');
});
$(".name input").blur(function(){
    if( this.value== ''){
        $(".name p").text('请输入用户名');
    }
});
$(".password input").blur(function(){
    if( this.value== ''){
        $(".password p").text('请输入密码');

    }
});
var  box = document.getElementById('pic');
var screenHeight = document.documentElement.clientHeight || document.body.clientHeight;
 
    box.style.height = screenHeight + 'px';
   
$(window).resize(function() { 
    var screenHeight = document.documentElement.clientHeight || document.body.clientHeight;
 
  box.style.height = screenHeight + 'px'
})

css

*{
    padding: 0;
    margin: 0;
    font-family: Microsoft YaHei;
}

input{
    outline: none;
}
.float_l{
    float:left;
}
.float_r{
    float: right;
}
.clearFix:after{
    display: block;
    font-size: 0;
    content: " ";
    clear: both;
    height: 0;

}
.bacBox{
    width: 1000px;
    height: 622px;
    margin: 0 auto;
    position: relative;
    overflow:hidden;
}
#pic{
    width: 100%;
    height: 100%;
}
.bac{
    position: absolute;
    top:0;
    left: 0;
}
.ad{
    font-size: 30px;
}
.loginContent{
    float: left;
    z-index: 2;
    width: 934px;
    height: 408px;
    position: absolute;
    top:16%;
    left: 50%;
    margin-left: -467px;
    border-radius: 10px;
}
/*left start*/
.logoBox{
    width: 584px;
    height: 100%;
    overflow:hidden;
    border-radius: 10px;
    position: relative;

}
.min_bac{
    width: 586;
    height: 412px;
    position: absolute;
    left: -2px;
    top:0;
}
.title{
    position: absolute;
    z-index: 4;
    left: 83px;
    top:90px;
}
.title h1{
    font-size: 51px;
    color: #c8280e;
    margin-top: 47px;
}
.bankName{
    font-size: 34px;
    color: #c8280e;
    position: absolute;
    top: -2px;
}
.logo{
    width: 43px;
    margin-right: 20px;
    vertical-align: middle;
}
/*left end*/
/*login_con start*/
.login_con{
    width: 350px;
    height: 100%;
    background: white;
    border-radius: 10px;

}
.personUiBox{
    text-align: center;
    margin-top: 53px;
}
.person_ui{
    width: 80px;

}
.name{
    position: relative;
}
.name input{
    width: 232px;
    height: 20px;
    font-size: 16px;
    padding:10px 0 10px 50px;
    padding-left: 50px;
    border-radius: 10px;
    border: 1px solid #c8280e;
    margin: 20px 0 25px 34px;
    color: #c8280e;
    position: relative;
    background: transparent;
    z-index: 20;

}
.password input{
    width: 232px;
    height: 20px;
    font-size: 16px;
    padding:10px 0 10px 50px;
    border-radius: 10px;
    border: 1px solid #c8280e;
    margin-left: 34px;
    position: relative;
    z-index: 20;
    background: transparent;
    color: #c8280e;

}
.people_fill{
    width: 30px;
    position: absolute;
    top: 25px;
    left: 42px;
}
.name_text{
    font-size: 16px;
    color: #c8280e;
    position: absolute;
    top: 30px;
    left: 85px;
    letter-spacing:1px;
}
.password{
    position: relative;
}
.passwordIcon{
    width: 42px;
    position: absolute;
    top: 0px;
    left: 35px;
}
.password_text{
    font-size: 16px;
    color: #c8280e;
    position: absolute;
    top: 10px;
    left: 85px;
    letter-spacing:1px;
}
.anniu{
    margin-top: 40px;
    margin: 40px 0  0 53px; 
}
.anniu a {
    display: inline-block;
    width: 100px;
    height: 38px;
    border-radius: 20px;
    top: 48px;
    color: white;
    background: #c8280e;
    font-size: 16px;
    text-align: center;
    line-height: 38px;
    margin-right: 40px;
    cursor: pointer;
}
.anniu a:hover{
    background: #af1a02;
    color: white;
}
/*login_con end*/
/*copy start*/
.copy{
    width: 600px;
    position: absolute;
    z-index: 3;
    bottom: 80px;
    left: 100px;
    font-size: 12px;
    color: #eece74;
}
/*copy end*/