Formatting elements without formatting similar elements throughout entire site
while writing your css for any html element you  need to be more specific. Suppose you are writing a css for an h1 tag which you want to get applied on that tag only , then be more specific by giving the h1 tag an id or class so that this css do not apply on other tags .More over you can alos filter your result as shown...
eg you have a h1 tag in your header region eg.

&lt;header&gt;
&lt;div id="first"&gt;
&lt;h1&gt; Hello There i am in header tag region 1&lt;/h1&gt;
&lt;/div&gt;
&lt;div id="second"&gt;
&lt;h1&gt; Hello There i am in header tag region 2 &lt;/h1&gt;
&lt;/div&gt;
&lt;/header&gt;    
&lt;h1&gt; How are you I am not in header tag&lt;/h1&gt;
CSS 
h1 {                            for last h1
color :red;
}
header #first h1 {
color:green;
}
header #second h1 {
color:blue;
}


..
output
Hello There i am in header tag region 1 and i will be green
Hello There i am in header tag region 2 and i will be green
How are you , i will be red
................
now if you write your css in this way..
h1 {
color : #262626 ;
}
then it will get applied to all the h1 tags...so you just need to be more specific 
you can also filter the tags by using pseudo classes...
you can learn about the css specificity on these links...

http://www.youtube.com/watch?v=0ZOV-KTTI1E

http://www.youtube.com/results?search_query=css+specificity&amp;oq=css+spe&amp;gs_l=youtube.1.2.0l4.1505.7011.0.9461.7.7.0.0.0.0.247.1042.1j4j2.7.0...0.0...1ac.1._LOJTw6jxBA