Two HTML tables side by side, centered on the page

Question

I have two tables on a page that I want to display side by side, and then center them within the page (actually within another div, but this is the simplest I could come up with):

<style>
  #outer { text-align: center; }
  #inner { text-align: left; margin: 0 auto; }
  .t { float: left; }
  table { border: 1px solid black; }
  #clearit { clear: left; }
</style>

<div id="outer">
  <p>Two tables, side by side, centered together within the page.</p>

  <div id="inner">
    <div class="t">
      <table>
        <tr><th>a</th><th>b</th></tr>
        <tr><td>1</td><td>2</td></tr>
        <tr><td>4</td><td>9</td></tr>
        <tr><td>16</td><td>25</td></tr>
      </table>
    </div>

    <div class="t">
      <table>
        <tr><th>a</th><th>b</th><th>c</th></tr>
        <tr><td>1</td><td>2</td><td>2</td></tr>
        <tr><td>3</td><td>5</td><td>15</td></tr>
        <tr><td>8</td><td>13</td><td>104</td></tr>
      </table>
    </div>

  </div>
  <div id="clearit">all done.</div>
</div>

I understand that it's something to do with the fact that the tables are floated, but I'm at a loss as to understand what I'm missing. There are many web pages that describe something like the technique I show here, but in any event it doesn't work; the tables cling stubbornly to the left hand margin.

Answer 1

Off the top of my head, you might try using the "margin: 0 auto" for #outer rather than #inner.

I often add background-color to my DIVs to see how they're laying out on the view. That might be a good way to diagnose what's going onn here.

Answer 2

The problem is that the DIV that should center your tables has no width defined. By default, DIVs are block elements and take up the entire width of their parent - in this case the entire document (propagating through the #outer DIV), so the automatic margin style has no effect.

For this technique to work, you simply have to set the width of the div that has margin:auto to anything but "auto" or "inherit" (either a fixed pixel value or a percentage).

Answer 3

Give your inner div a width.

EXAMPLE

Change your CSS:

<style>
#outer { text-align: center; }
#inner { text-align: left; margin: 0 auto; }
.t { float: left; }
table { border: 1px solid black; }
#clearit { clear: left; }
</style>

To this:

<style>
#outer { text-align: center; }
#inner { text-align: left; margin: 0 auto; width:500px }
.t { float: left; }
table { border: 1px solid black; }
#clearit { clear: left; }
</style>

Answer 4

The problem is that you need to give #inner a set width (anything but auto or inherit). The margin: 0 auto; trick only works if the inner element is narrower than its container element. Without being given a width, #inner is automatically expanding to the full width of #outer, which causes its contents to be flush left.

Answer 5

If it was me - I would do something like this:

<style type="text/css" media="screen">
 table { border: 1px solid black;float:left;width:148px;}
 #table_container{width:300px;margin:0 auto;}
</style>

With the table like:

<div id="table_container">
  <table>
    <tr>
      <th>a</th>
      <th>b</th>
    </tr>
    <tr>
      <td>1</td>
      <td>2</td>
    </tr>
    <tr>
      <td>4</td>
      <td>9</td>
    </tr>
    <tr>
      <td>16</td>
      <td>25</td>
    </tr>
  </table>
  <table>
    <tr>
      <th>a</th>
      <th>b</th>
    </tr>
    <tr>
      <td>1</td>
      <td>2</td>
    </tr>
    <tr>
      <td>4</td>
      <td>9</td>
    </tr>
    <tr>
      <td>16</td>
      <td>25</td>
    </tr>
  </table>
</div>

Answer 6

<style>
#outer { text-align: center; }
#inner { width:500px; text-align: left; margin: 0 auto; }
.t { float: left; width:240px; border: 1px solid black;}
#clearit { clear: both; }
</style>

Answer 7

Unfortunately, all of these solutions rely on specifying a fixed width. Since the tables are generated dynamically (statistical results pulled from a database), the width can not be known in advance.

The desired result can be achieved by wrapping the two tables within another table:

<table align="center"><tr><td>
... the two tables ...
</td></tr></table>

and the result is a perfectly centered pair of tables that responds fluidly to arbitrary widths and page (re)sizes (and the align="center" table attribute could be hoisted out into an outer div with margin autos).

I conclude that there are some layouts that can only be achieved with tables.

Answer 8

I realize this is an ancient question, but here goes anyway.

The following will work in compliant browsers and IE8 in standards mode (i.e. with a doctype set).

#inner {text-align:center;}
.t {display:inline-block;}

Unfortunately, there's really no way to tweak it to work in IE6. For IE7, adding a zoom:1 to the .t divs (via a conditional comment) might help, but I don't have IE7 available for testing at the moment.