Full CSS Property Table

Make a DIV fill an entire table cell

The following code works on IE 8, IE 8's IE 7 compatibility mode, and Chrome (not tested elsewhere):

<table style="width:100px"> <!-- Not actually necessary; just makes the example text shorter -->
   <tr><td>test</td><td>test</td></tr>
   <tr>
      <td style="padding:0;">
         <div style="height:100%; width:100%; background-color:#abc; position:relative;">
            <img style="left:90px; position:absolute;" src="../Content/Images/attachment.png"/>
            test of really long content that causes the height of the cell to increase dynamically
         </div>
      </td>
      <td>test</td>
   </tr>
</table>

You said in your original question that setting width and height to 100% didn't work, though, which makes me suspect that there is some other rule overriding it. Did you check the computed style in Chrome or Firebug to see if the width/height rules were really being applied?

Edit

How foolish I am! The div was sizing to the text, not to the td. You can fix this on Chrome by making the div display:inline-block, but it doesn't work on IE. That's proving trickier...

Pure css table styling

Better you div for this style.

If you want table, make design like this.

By default the inner tables ( having different heights ) will look similar to one you want.

<table> 
    <tr> 
        <td> 
            <table height="x" style="background:">
                <tr><td>Row 1</td> </tr>
                <tr><td>Row 1</td> </tr>
                <tr><td>Row 1</td> </tr>
                <tr><td>Row 1</td> </tr>
            </table>
        </td>
        <td> 
            <table height="y" style="background:">
                <tr><td>Row 1</td> </tr>
                <tr><td>Row 1</td> </tr>
                <tr><td>Row 1</td> </tr>
                <tr><td>Row 1</td> </tr>
            </table>
        </td>
    </tr>
</table>

HTML table with 100% width, with vertical scroll inside tbody

In order to make <tbody> element scrollable, we need to change the way it's displayed on the page i.e. using display: block; to display that as a block level element.

Since we change the display property of tbody, we should change that property for thead element as well to prevent from breaking the table layout.

So we have:

thead, tbody { display: block; }

tbody {
    height: 100px;       /* Just for the demo          */
    overflow-y: auto;    /* Trigger vertical scroll    */
    overflow-x: hidden;  /* Hide the horizontal scroll */
}

Web browsers display the thead and tbody elements as row-group (table-header-group and table-row-group) by default.

Once we change that, the inside tr elements doesn't fill the entire space of their container.

In order to fix that, we have to calculate the width of tbody columns and apply the corresponding value to the thead columns via JavaScript.

Auto Width Columns

Here is the jQuery version of above logic:

// Change the selector if needed
var $table = $('table'),
    $bodyCells = $table.find('tbody tr:first').children(),
    colWidth;

// Get the tbody columns width array
colWidth = $bodyCells.map(function() {
    return $(this).width();
}).get();

// Set the width of thead columns
$table.find('thead tr').children().each(function(i, v) {
    $(v).width(colWidth[i]);
});    

And here is the output (on Windows 7 Chrome 32):

WORKING DEMO.

Full Width Table, Relative Width Columns

As the Original Poster needed, we could expand the table to 100% of width of its container, and then using a relative (Percentage) width for each columns of the table.

table {
    width: 100%; /* Optional */
}

tbody td, thead th {
    width: 20%;  /* Optional */
}

Since the table has a (sort of) fluid layout, we should adjust the width of thead columns when the container resizes.

Hence we should set the columns' widths once the window is resized:

// Adjust the width of thead cells when *window* resizes
$(window).resize(function() {
    /* Same as before */ 
}).resize(); // Trigger the resize handler once the script runs

The output would be:

WORKING DEMO.

Browser Support and Alternatives

I've tested the two above methods on Windows 7 via the new versions of major Web Browsers (including IE10+) and it worked.

However, it doesn't work properly on IE9 and below.

That's because in a table layout, all elements should follow the same structural properties.

By using display: block; for the <thead> and <tbody> elements, we've broken the table structure.

Redesign layout via JavaScript

One approach is to redesign the (entire) table layout. Using JavaScript to create a new layout on the fly and handle and/or adjust the widths/heights of the cells dynamically.

For instance, take a look at the following examples:

• jQuery .floatThead() plugin (a floating/locked/sticky table header plugin)
• jQuery Scrollable Table plugin. (source code on github)
• jQuery .FixedHeaderTable() plugin (source code on github)
• DataTables vertical scrolling example.

Nesting tables

This approach uses two nested tables with a containing div. The first table has only one cell which has a div, and the second table is placed inside that div element.

Check the Vertical scrolling tables at CSS Play.

This works on most of web browsers. We can also do the above logic dynamically via JavaScript.

Table with fixed header on scroll

Since the purpose of adding vertical scroll bar to the <tbody> is displaying the table header at the top of each row, we could position the thead element to stay fixed at the top of the screen instead.

Here is a Working Demo of this approach performed by Julien.

It has a promising web browser support.

And here a pure CSS implementation by Willem Van Bockstal.

The Pure CSS Solution

Here is the old answer. Of course I've added a new method and refined the CSS declarations.

Table with Fixed Width

In this case, the table should have a fixed width (including the sum of columns' widths and the width of vertical scroll-bar).

Each column should have a specific width and the last column of thead element needs a greater width which equals to the others' width + the width of vertical scroll-bar.

Therefore, the CSS would be:

table {
    width: 716px; /* 140px * 5 column + 16px scrollbar width */
    border-spacing: 0;
}

tbody, thead tr { display: block; }

tbody {
    height: 100px;
    overflow-y: auto;
    overflow-x: hidden;
}

tbody td, thead th {
    width: 140px;
}

thead th:last-child {
    width: 156px; /* 140px + 16px scrollbar width */
}

Here is the output:

WORKING DEMO.

Table with 100% Width

In this approach, the table has a width of 100% and for each th and td, the value of width property should be less than 100% / number of cols.

Also, we need to reduce the width of thead as value of the width of vertical scroll-bar.

In order to do that, we need to use CSS3 calc() function, as follows:

table {
    width: 100%;
    border-spacing: 0;
}

thead, tbody, tr, th, td { display: block; }

thead tr {
    /* fallback */
    width: 97%;
    /* minus scroll bar width */
    width: -webkit-calc(100% - 16px);
    width:    -moz-calc(100% - 16px);
    width:         calc(100% - 16px);
}

tr:after {  /* clearing float */
    content: ' ';
    display: block;
    visibility: hidden;
    clear: both;
}

tbody {
    height: 100px;
    overflow-y: auto;
    overflow-x: hidden;
}

tbody td, thead th {
    width: 19%;  /* 19% is less than (100% / 5 cols) = 20% */
    float: left;
}

Here is the Online Demo.

Note: This approach will fail if the content of each column breaks the line, i.e. the content of each cell should be short enough.

In the following, there are two simple example of pure CSS solution which I created at the time I answered this question.

Here is the jsFiddle Demo v2.

Old version: jsFiddle Demo v1

HTML table full width with margin

use calc() to calculate the intended width:

table {
    margin: auto;
    width: calc(100% - 40px);
}

http://jsfiddle.net/EXS76/1/

Making the textarea to take up full width in css table layout

The nature of your nested markup isn't wholly valid- in addition the logic conflicts somewhat.

Solution 1: table-caption

What you are effectively after is a CSS version of colspan, you can achieve this by changing your HTML to that below, and implementing table-caption

.full_width {

  width: 100%

}

.table {

  display: table;

  width: 100%;

}

.table_row {

  display: table-row;

  width: 100%;

}

.table_cell {

  display: table-cell

}

.label {

  display: block

}

.two_cell {

  width: 48%;

}

#company_cell {

  padding-left: 4%;

}

.table_cell {

  padding-bottom: 18px

}

.table_caption {

  display: table-caption;

  caption-side: bottom;

}

<form class="table" method="post">

  <div class="table_row">

    <div class="table_cell">

      <span>Name</span>

      <input name="name" class="full_width" type="text" value="" />

    </div>

    <div class="table_cell">

      <span>Company</span>

      <input name="company" class="full_width" type="text" value="" />

    </div>

  </div>

  <div class="table_caption">

    <span>Comment</span>

    <br />

    <textarea name="comment" class="full_width" value="SEND"></textarea>

  </div>

</form>

.full_width{width: 100%}

.table{ display: table;}

.table_row{display: table-row;}

.table_cell{display:table-cell;padding-bottom: 18px;}

.wrapper_cont{width: 48%}

#cell2{padding-left: 4%}

.label{display:block}

<div class="table full_width">

    <div class="table_cell full_width">

        <div id="does_something_important">

            <div id="does_something_important2">

                <form class="table full_width" method="post">

                    <div class="table_row full_width">

                            <div id="cell1" class="table_cell wrapper_cont">

                                <span class="label">Name</span>

                                <input class="full_width" value="Michael" type="text"/>

                            </div>

                            <div id="cell2" class="table_cell wrapper_cont">

                                <span class="label">Email</span>

                                <input class="full_width" type="text"/>

                            </div>

                    </div>

                     <div class="table_row full_width">

                            <div id="cell1" class="table_cell wrapper_cont">

                                <span class="label">Name</span>

                                <input class="full_width" value="Michael" type="text"/>

                            </div>

                            <div id="cell2" class="table_cell wrapper_cont">

                                <span class="label">Email</span>

                                <input class="full_width" type="text"/>

                            </div>

                    </div>

                </form>

            </div>

        </div>

    </div>

</div>