Whit it? Different results for same code

Question

It's ok ...:

but:

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

Answer 1

It looks like you are more zoomed in on the 1st table than in the 2nd. You can try zooming in on the second, and the bordering should reappear.