CSS定位，需要一些建議

Question

這是我的HTML代碼

<div id="container">
        <div id="topleft"></div>
        <div id="topright"></div>
        <div id="bottomleft"></div>
        <div id="bottomright"></div>
    </div>

這是我的css代碼

#container{
    width: 400px;
    height: 400px;
    background-color: red;
    margin: 0 auto;

}

#topright{
    width: 50px;
    height: 50px;
    background-color: black;
    position: relative;
    top:0px;
    right:0px;
}
#topleft{
    width: 50px;
    height: 50px;
    background-color: black;
    position:relative;
    top:0px;
    left:350px;
}

#bottomright{
    width: 50px;
    height: 50px;
    background-color: black;
    position: relative;
    top:250px;
    right:0px;
}
#bottomleft{
    width: 50px;
    height: 50px;
    background-color: black;
    position:relative;
    top:250px;
    left:350px;
}

這是輸出http://s23.postimg.org/dhgy9mpq3/image.png

我需要獲得的是，所有4個黑色方塊都位於紅色方塊的角落，就像在這張圖片中一樣，我應該更改或添加代碼？ THX http://postimg.org/image/r5kv15l5v/

Answer 1

添加position:relative對於#container和position:absolute到內部div。

您可以將常用屬性與逗號結合使用，例如

#bottomright,#bottomleft{css properties}

CSS：

#container {
    position: relative;
}
#container > div {
    width: 50px;
    height: 50px;
    background-color: black;
    position: absolute;
}
#bottomright, #bottomleft {
    bottom:0;
}
#topright, #topleft {
    top:0;
}
#bottomleft, #topleft {
    left:0;
}
#bottomright, #topright {
    right:0;
}

DEMO在這里。

Answer 2

解

為什么你的css失敗：對於底部對齊，使用bottom:0;left:0; 而不是top和right ....這是正確的語義，否則失敗的概念position ...同時，讓孩子absolute和父母relative ！ :)

 #container {
        width: 400px;
        height: 400px;
        background-color: red;
        margin: 0 auto;
        position: relative;
    }
    #topright {
        width: 50px;
        height: 50px;
        background-color: black;
        position: absolute;
        top:0px;
        right:0px;
    }
    #topleft {
        width: 50px;
        height: 50px;
        background-color: black;
        position:absolute;
        top:0px;
        left:0;
    }
    #bottomright {
        width: 50px;
        height: 50px;
        background-color: black;
        position: absolute;
        bottom:0;
        right:0px;
    }
    #bottomleft {
        width: 50px;
        height: 50px;
        background-color: black;
        position:absolute;
        bottom:0;
        left:0;
    }

Answer 3

使#container位置relative 。 而div里面那absolute 。

完整代碼

#container{
    width: 400px;
    height: 400px;
    background-color: red;
    margin: 0 auto;
    position: relative; //change

}

#topright{    
    width: 50px;
    height: 50px;
    background-color: black;
    position: absolute; //change
    top:0px;
    right:0px;
}
#topleft{
    width: 50px;
    height: 50px;
    background-color: black;
    position:absolute; //change
    top:0px;
    left:0px;  //change
}

#bottomright{
    width: 50px;
    height: 50px;
    background-color: black;
    position: absolute;
    bottom:0px; //change
    right:0px;
}
#bottomleft{
    width: 50px;
    height: 50px;
    background-color: black;
    position:absolute; //change
    bottom:0px; //change
    left:0px; //change
}

Answer 4

演示

#container{
    width: 400px;
    height: 400px;
    background-color: red;
    margin: 0 auto;
    position: relative;

}

#topright{    
    width: 50px;
    height: 50px;
    background-color: black;
    position: absolute;
    top:0px;
    right:0px;
}
#topleft{
    width: 50px;
    height: 50px;
    background-color: black;
    position:absolute;
    top:0px;
    left:0;
}

#bottomright{
    width: 50px;
    height: 50px;
    background-color: black;
    position: absolute;
    bottom:0px;
    right:0px;
}
#bottomleft{
    width: 50px;
    height: 50px;
    background-color: black;
    position:absolute;
    bottom:0;
    left:0;
}

Answer 5

以下css將起作用

#container {
    background-color: #FF0000;
    height: 400px;
    margin: 0 auto;
    position: relative;
    width: 400px;
}
#topleft {
    background-color: #000000;
    height: 50px;
    left: 0;
    position: absolute;
    top: 0;
    width: 50px;
} 

#topright {
    background-color: #000000;
    height: 50px;
    position: absolute;
    right: 0;
    top: 0;
    width: 50px;
}
#bottomleft {
    background-color: #000000;
    height: 50px;
    left: 350px;
    position: absolute;
    top: 350px;
    width: 50px;
}
#bottomright {
    background-color: #000000;
    height: 50px;
    left: 0;
    position: absolute;
    top: 350px;
    width: 50px;
}