Affecting the parent only - css

Question

Lets get straight to the point, I have created this example to better get my point across:
Demo Here
HTML:
Table 1
<table class="testClass">
<tr>
<td>Inner table
<table>
<tr>
<td>Hello</td>
<td>Testing testing</td>
<td>Bye</td>
</tr>
</table>
</td>
</tr>
</table>
<br />
<br />
<br />Table 2
<table class="testClass">
<tr>
<td colspan="3">stuff</td>
</tr>
<tr>
<td>Left</td>
<td>Middle</td>
<td>Right</td>
</tr>
</table>
CSS:
table {
border: 2px solid red;
width: 100%;
}
td {
border: 2px solid blue;
}
/* Relative CSS */
.testClass tr:last-child td:nth-child(1) {
width: 15px;
}
.testClass tr:last-child td:nth-child(2) {
width: auto;
}
.testClass tr:last-child td:nth-child(3) {
width: 15px;
}
So we have 2 tables, both with the same class. Table 1 has a table within it where as Table 2 does not.
The problem I'm finding with this is using the CSS I have created I am unable to stop the styles for .testClass from affected the child table (Inner table). I was thinking that :not() could be used but am unable to find a solution using it tho I feel this shouldn't be that hard.
Is it possible to only affect the parent within the styles from the parent getting to the child table?
Note: The CSS can only be changed not the HTML. CSS3 can be used!
I hope this made some sense, if I need to make it clearer please leave a comment.

Answer 1

Select the first level child and apply it.
.testClass > tbody > tr:last-child > td:nth-child(1) {
width: 15px;
}
.testClass > tbody > tr:last-child > td:nth-child(2) {
width: auto;
}
.testClass > tbody > tr:last-child > td:nth-child(3) {
width: 15px;
}
DEMO

Answer 2

maybe this way : http://jsfiddle.net/urryfof5/7/
Basically you call the last-child table from the body and add > so it won't affect nested tables inside:
body > table:last-child (and follow it with your css)

Answer 3

You could add style-declarations like
table table { border: none; }
to override styles from the parent table-declaration. This way, no nested tables will have the border. The same thing applies for the tds.
Another solution would be:
table:not(.testClass) {
border: 0px none;
}
which removes the border for all tables that do not have the testClass applied. I tested and saw this work (in another version of the below Fiddle).
Here's a Fiddle with your code with two additional declarations, removing the borders for the inner table:
http://jsfiddle.net/erlingormar/bk6m4w5d/#base