Whit it? Different results for same code

It's ok ...: http://ift.tt/1MCvQg7

but: http://ift.tt/1MY97Io

Why it? I'm developing a web site, and it's a trouble, a really trouble. kkk'

The code:

<!-- CSS goes in the document HEAD or added to your external stylesheet -->
<style type="text/css">
table.gridtable {
        font-family: verdana,arial,sans-serif;
        font-size:11px;
        color:#333333;
        border-width: 1px;
        border-color: #666666;
        border-collapse: collapse;
}
table.gridtable th {
        border-width: 1px;
        padding: 8px;
        border-style: solid;
        border-color: #666666;
        background-color: #dedede;
}
table.gridtable td {
        border-width: 1px;
        padding: 8px;
        border-style: solid;
        border-color: #666666;
        background-color: #ffffff;
}
</style>
<!-- Table goes in the document BODY -->
<table class="gridtable">
<tr>
        <th>Info Header 1</th><th>Info Header 2</th><th>Info Header 3</th>
</tr>
<tr>
        <td>Text 1A</td><td>Text 1B</td><td>Text 1C</td>
</tr>
<tr>
        <td>Text 2A</td><td>Text 2B</td><td>Text 2C</td>
</tr>
</table>

Why it?