[html] Make a div fill up the remaining width

Up-to-date solution (October 2014) : ready for fluid layouts

Introduction:

This solution is even simpler than the one provided by Leigh. It is actually based on it.

Here you can notice that the middle element (in our case, with "content__middle" class) does not have any dimensional property specified - no width, nor padding, nor margin related property at all - but only an overflow: auto; (see note 1).

The great advantage is that now you can specify a max-width and a min-width to your left & right elements. Which is fantastic for fluid layouts.. hence responsive layout :-)

note 1: versus Leigh's answer where you need to add the margin-left & margin-right properties to the "content__middle" class.

Code with non-fluid layout:

Here the left & right elements (with classes "content__left" and "content__right") have a fixed width (in pixels): hence called non-fluid layout.

Live Demo on http://jsbin.com/qukocefudusu/1/edit?html,css,output

<style>
    /*
     * [1] & [3] "floats" makes the 2 divs align themselves respectively right & left
     * [2] "overflow: auto;" makes this div take the remaining width
     */
    .content {
        width: 100%;
    }
    .content__left {
        width: 100px;
        float: left; /* [1] */
        background-color: #fcc;
    }
    .content__middle {
        background-color: #cfc;
        overflow: auto; /* [2] */
    }
    .content__right {
        width: 100px;
        float: right; /* [3] */
        background-color: #ccf;
    }
</style>

<div class="content">
    <div class="content__left">
        left div<br/>left div<br/>left div<br/>left div<br/>left div<br/>left div<br/>
    </div>
    <div class="content__right">
        right div<br/>right div<br/>right div<br/>right div<br/>
    </div>
    <div class="content__middle">
        middle div<br/>middle div<br/>middle div<br/>middle div<br/>middle div<br/>middle div<br/>middle div<br/>middle div<br/>middle div<br />bit taller
    </div>
</div>

Code with fluid layout:

Here the left & right elements (with classes "content__left" and "content__right") have a variable width (in percentages) but also a minimum and maximum width: hence called fluid layout.

Live Demo in a fluid layout with the max-width properties http://jsbin.com/runahoremuwu/1/edit?html,css,output

<style>
    /*
     * [1] & [3] "floats" makes the 2 divs align themselves respectively right & left
     * [2] "overflow: auto;" makes this div take the remaining width
     */
    .content { 
        width: 100%; 
    }
    .content__left { 
        width: 20%; 
        max-width: 170px;  
        min-width: 40px;  
        float: left; /* [1] */
        background-color: #fcc; 
     }
    .content__middle { 
        background-color: #cfc; 
        overflow: auto; /* [2] */
    }
    .content__right { 
        width: 20%; 
        max-width: 250px; 
        min-width: 80px; 
        float: right; /* [3] */
        background-color: #ccf; 
    }
</style>

<div class="content">
    <div class="content__left">
        max-width of 170px & min-width of 40px<br />left div<br/>left div<br/>left div<br/>left div<br/>left div<br/>left div<br/>
    </div>
    <div class="content__right">
        max-width of 250px & min-width of 80px<br />right div<br/>right div<br/>right div<br/>right div<br/>
    </div>
    <div class="content__middle">
        middle div<br/>middle div<br/>middle div<br/>middle div<br/>middle div<br/>middle div<br/>middle div<br/>middle div<br/>middle div<br />bit taller
    </div>
</div>

Browser Support

Tested on BrowserStack.com on the following web browsers:

• IE7 to IE11
• Ff 20, Ff 28
• Safari 4.0 (windows XP), Safari 5.1 (windows XP)
• Chrome 20, Chrome 25, Chrome 30, Chrome 33,
• Opera 20