Hi John,

Please find answers of your question.

1 Table-fixed attribute in css

Css can be applied to any html element in 3 differnet manners

      1. element ID attribute
      2. element class attribute.
      3. inline stylesheet.

     1. id attribute : this method is used when you want to apply specific css to an element. for example if you want to apply color:red to a <h1> tag you will define that color property in css and it will get applied to <h1>  tag
 

<style>
#redcolor
{
color:red;
font-size:30px;
}
</style>

<h1 id="redcolor">Hello world</h1>

   2. element class attribute : this method is used when you want to apply a single css on multiple items in your html. a . is used to define css in following way
 

<style>
.redcolor
{
color:red;
font-size:30px;
}
</style>

<h1 class="redcolor">Hello world</h1>

<div class="redcolor">My Test Css</div>

here you can see that I have defined a single css redcolor but I have used . instead of # while defining the css and it will be applied to both items.

3. inline style : This method is used when you have very minimum css requirement and you don't want to define them in any external stylesheet. 
 

<h1 style="color:black">Hello world</h1>

2. If you understood my first point here is your question's answer. If you want to apply to an specific table you need to define id attribute of that table and you need to define css for that id in following way
 

<style>
#mytable
{
table-layout: fixed;
}
</style>

<table id="redcolor">
   <tr>
        <td>
       </td>
    </tr>
</table>

3. You can define css as extenal stylesheet  by creating a customstyle.css file and upload that in static resource section. name it as style_resources and add following line in your visualforce page.
 

<apex:stylesheet value="{!URLFOR($Resource.style_resources, 'customstyle.css')}"/>

Thanks,
Himanshu

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