please see this link

i browsed this website New Zealand's venetian blinds and roller blinds specialists - Venluree and found the layout very different in terms of how the 4 background images are placed and i am trying create that kind of layout for practicing purpose of css layouts the file that i have created is at

i have got it working however i am not very sure if the procedure i have done with my css code using z-index is the right way to go about

also my question is about the height of the layout, if the layout of the page increases or decreases the brown and green images on the left and right should grow or reduce in height according to the content in the center which has a white background

as of know i have set min-height: 990px; for div1

can someone look at my code and suggest what is the best and the right way to go about writting the css code for this kind of layout