在前面一篇中我们介绍了纯CSS实现tooltip提示框,通俗的讲也就是CSS箭头及形状
不过注意一点是,他始终是一个元素,只是通过CSS实现的,今天我们要说的是给这个“tooltip提示框”整体加一个边框,下面是是一篇完成的截图(不了解的可以看看:纯CSS实现tooltip提示框,CSS箭头及形状):
首先像:after一样我们介绍另外一个CSS中“ :before ”选择器
定义和用法:(参考w3school:before选择器)
:before 选择器在被选元素的内容前面插入内容,使用 content 属性来指定要插入的内容
例:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
p:before
{
content:"台词:-";
background-color:yellow;
color:red;
font-weight:bold;
}
下面一步一步实现给该tooltip整体添加边框:
首先HTML代码:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
<body> <div class="demo"></div> </body>
让我们来设置盒子的样式
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
<style> .demo{ background-color: gray; height: 100px; position: relative; width: 100px; } </style>
截图:
(其中具体的position的设定缘由大家看前一篇的解释,谢谢~~)
接着“引入”箭头,注意这里要同时用到“ :after ”和“ :before ”两个CSS选择器同时产生不同尺寸的箭头,基本样式:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
<style> .demo{ background-color: gray; height: 100px; position: relative; width: 100px; } .demo:after,.demo:before{ content:''; position:absolute; } .demo:after{ height:20px; width:20px; background:yellow; } .demo:before{ height:30px; width:30px; background:green; } </style>
截图:
继续,我们要给黄色方块和绿色方块设置边框,样式:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
<style> .demo{ background-color: gray; height: 100px; position: relative; width: 100px; } .demo:after,.demo:before{ content:''; position:absolute; } .demo:after{ height:20px; width:20px; background:yellow; border:5px solid lightgreen; } .demo:before{ height:30px; width:30px; background:green; border:5px solid red; } </style>
截图:
再者我们将黄色方块和绿色方块内容去掉,通过去掉:after和:before的height、width,仅剩下浅绿色方框和红色方框,分别是黄色方块、绿色方块的边框,样式:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
<style> .demo{ background-color: gray; height: 100px; position: relative; width: 100px; } .demo:after,.demo:before{ content:''; position:absolute; } .demo:after{ //height:20px; //width:20px; background:yellow; border:5px solid lightgreen; } .demo:before{ //height:30px; //width:30px; background:green; border:5px solid red; } </style>
截图:
这里注意红色的边框被覆盖了,所以我们需要给浅绿色方块和红色方块增加像素,但是增加的像素值彼此不相同,为后续做准备,样式:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
<style> .demo{ background-color: gray; height: 100px; position: relative; width: 100px; } .demo:after,.demo:before{ content:''; position:absolute; } .demo:after{ //height:20px; //width:20px; background:yellow; border:10px solid lightgreen; } .demo:before{ //height:30px; //width:30px; background:green; border:15px solid red; } </style>
截图:
注意,这里我们将浅绿色的边框像素值由5px改为了10px;而红色边框由5px改为了15px,如上图,但值得小心的是区分这里的浅绿色方框、红色方框与上面的黄色方块、绿色方块样子相同,但性质却截然不同,一种是边框,一种是方块~~而实现箭头是通过边框来实现的,原理参见上一篇纯CSS实现tooltip提示框,CSS箭头及形状
下面来实现箭头,样式:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
<style> .demo{ background-color: gray; height: 100px; position: relative; width: 100px; } .demo:after,.demo:before{ content:''; position:absolute; } .demo:after{ //height:20px; //width:20px; //background:yellow; //border:10px solid lightgreen; border:10px solid transparent; border-top-color:lightgreen; } .demo:before{ //height:30px; //width:30px; //background:green; //border:15px solid red; border:15px solid transparent; border-top-color:red; } </style>
截图:
然后我们通过position:absolute的top、right、bottom、left,以下简称TRBL来设置箭头及边框(这里指红色边框,即将成为箭头的边框)的位置,样式:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
<style> .demo{ background-color: gray; height: 100px; position: relative; width: 100px; } .demo:after,.demo:before{ content:''; position:absolute; } .demo:after{ //height:20px; //width:20px; //background:yellow; //border:10px solid lightgreen; border:10px solid transparent; border-top-color:lightgreen; top:100px; left:20px; } .demo:before{ //height:30px; //width:30px; //background:green; //border:15px solid red; border:15px solid transparent; border-top-color:red; top:100px; left:15px; } </style>
截图:
接着来设置灰色盒子的边框为红色,边框大小与红色相同,同时将箭头浅绿色改为灰色,使其看起来浑然一体,样式:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
<style> .demo{ background-color: gray; height: 100px; position: relative; width: 100px; border:2.75px solid red; } .demo:after,.demo:before{ content:''; position:absolute; } .demo:after{ //height:20px; //width:20px; //background:yellow; //border:10px solid lightgreen; border:10px solid transparent; border-top-color:gray; top:100px; left:20px; } .demo:before{ //height:30px; //width:30px; //background:green; //border:15px solid red; border:15px solid transparent; border-top-color:red; top:100px; left:15px; } </style>
截图:
其中灰色盒子的边框2.75px与箭头边框红色部分的宽度计算,大家自己捉摸捉摸哈~~数学问题!
至此,我们的续写,给“tooltip提示框”添加个边框到此结束!具体颜色样式大家可以随自己要求自己做修改~~
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