How to position absolute inside a div?

user_139468 0
Viewed 197436

I'm having a strange problem positioning a set of divs inside another div. I think it will be best to describe it with an image:

image

Inside the black (#box) div there are two divs (.a, .b) that have to positioned in the same place. What I'm trying to achieve is pictured in the first image, second one is the effect I get. It looks like if the divs were floated without clearing or something, which is obviously not the case. Any ideas would be welcome!

Here's the code for this sample:

CSS:

#box {
    background-color: #000;
    position: relative;
    padding: 10px;
    width: 220px;
}

.a {
    width: 210px;
    position: absolute;
    top: 10px;
    left: 10px;
    background-color: #fff;
    padding: 5px;
}

.b {
    width: 210px;
    position: absolute;
    top: 10px;
    left: 10px;
    background-color: red;
    padding: 5px;
}

#after {
    background-color: yellow;
    padding: 10px;
    width: 220px;
}

HTML:

    <div id="box">
        <div class="a">Lorem</div>
        <div class="b">Lorem</div>
    </div>

    <div id="after">Hello world</div>
positioning css
4 Answers

The absolute divs are taken out of the flow of the document so the containing div does not have any content except for the padding. Give #box a height to fill it out.

#box {
    background-color: #000;
    position: relative;
    padding: 10px;
    width: 220px;
    height:30px;
}
user_1102020

One of #a or #b needs to be not position:absolute, so that #box will grow to accommodate it.

So you can stop #a from being position:absolute, and still position #b over the top of it, like this:

 #box {
        background-color: #000;
        position: relative;     
        padding: 10px;
        width: 220px;
    }
    
    .a {
        width: 210px;
        background-color: #fff;
        padding: 5px;
    }
    
    .b {
        width: 100px; /* So you can see the other one */
        position: absolute;
        top: 10px; left: 10px;
        background-color: red;
        padding: 5px;
    }
    
    #after {
        background-color: yellow;
        padding: 10px;
        width: 220px;
    }
    <div id="box">
        <div class="a">Lorem</div>
        <div class="b">Lorem</div>
    </div>
    <div id="after">Hello world</div>

(Note that I've made the widths different, so you can see one behind the other.)

Edit after Justine's comment: Then your only option is to specify the height of #box. This:

#box {
    /* ... */
    height: 30px;
}

works perfectly, assuming the heights of a and b are fixed. Note that you'll need to put IE into standards mode by adding a doctype at the top of your HTML

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
          "http://www.w3.org/TR/html4/strict.dtd">

before that works properly.

user_218860

The problem is described (among other) in this article.

#box is relatively positioned, which makes it part of the "flow" of the page. Your other divs are absolutely positioned, so they are removed from the page's "flow".

Page flow means that the positioning of an element effects other elements in the flow.

In other words, as #box now sees the dom, .a and .b are no longer "inside" #box.

To fix this, you would want to make everything relative, or everything absolute.

One way would be:

.a {
   position:relative;
   margin-top:10px;
   margin-left:10px;
   background-color:red;
   width:210px;
   padding: 5px;
}
user_1055360
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