mainleft

#mainleft {
width:33%;
float:left;
background:#fff;
padding-bottom:10px;
	}

Marketing teams input produce cross purposing in view of goal alignments due to knowlege paucity, necessitating workflow education and orientation. Media sourcing as an acquistion strategy is counterproductive in a internet environment in virtual component methodology. Imaging through ideals rather than real world branding, is a perilous undertaking with negative results. Branding strategies generating motion as activity without reproducible results is a ultimately futile effort if left in place.

maincenter

#maincenter {
width:34%;
float:left;
background:#fff;
padding-bottom:10px;
	}

A much simpler and potentially more useful technique that then 4 column technique using float:left instead of position:absloute. It suffers from needing percentage widths for each column, and from potential column wrapping when the browser window is narrowed.

Scroll down for the source.

Enterprise engenderment accelerates initiative platforms, reducing staffing components, integration of technical accessibility, resulting in bottom line pluralisms, benefit-wise. Incidental re-sizing staff requirements through attrition can be accelerated by paridigm shifts and focusing on core suitability and cross-training.

mainright

#mainright {
width:33%;
float:left;
background:#fff;
padding-bottom:10px;
	}

This page is part of CSS Layout Techniques, a resource for web developers and designers.

Other Layout Techniques:
3 columns, the holy grail
2 columns, ALA style
4 columns, all fluid
3 columns, all fluid
static width and centered
nested float

Does it validate?