well Browser reads the HTML top to buttom, now if you build web page as placing the content in Text or image box and code by their position by PX. then u can put the buttom code on top of the HTML therefore in that way u may find the page loading buttom up...
y do u read...book page from top to bottom not from bottom to top..
and also when u write webpage....u code form top to bottom..not from bottom to top..
so it is interpreted in same way by browser..