Under IE: float attribute will affect the value of offsetTop_javascript skills

Because I need to locate the height of an HTML element (for example: div) from the top of the page, I want to use offsetTop to get the value. However, I find that if float:left; is used in CSS, the value will be obtained. no the same.

Float:left is not used; the value obtained is the normal value of 200;
nbsp;html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

body {margin:0;padding: 0;}
#Top {height:100px;}
#Main {padding:100px;} #IECN {width:200px;height:50px;background:#f00;color:#fff;}



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nbsp;html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

Used float :left;, the value became 100, which was 100 less for no reason


The impact of Float on offsetTop





#Main {padding:100px;float:left;} uses the float attribute, The value of offsetTop obtained is only 100, which is 100 less for no reason.