CSS圆角不起作用-为什么不起作用？

Question

<div id="main-solutions">
   <div id="main-solutions-top-left"></div>
   <div id="main-solutions-top-right"></div>
   <div id="main-solutions-body">
       blah blah blah
   </div>
</div>

css

#main-solutions {
}

#main-solutions-top-left {
    position: absolute;
    top: 0px;
    left: 0px;
    background: url('../images/Top-Left-Gray-Corner.gif') no-repeat top left;
    width: 434px;
    height: 15px;
}

#main-solutions-top-right {
    position: absolute;
    top: 0;
    right: 0;
    background: url('../images/Top-Right-Gray-Corner.gif') no-repeat top right;
    width: 434px;
    height: 15px;
}

#main-solutions-body {
    background: url('../images/Gray-Gradient.jpg') repeat-x;
}

I'm expecting to see that main-solutions has two absolutely positioned divs at the top left and right with my rounded corner image, and then followed by the body with the gradient, but when I use HTML element browsers, the top-left and top-right div are not appearing at all, very confused, why are those divs being disregarded?

UPDATE (for others confused by answer):

At the root of my issue is I didn't understand that both absolute and relative define a new coordinate system for their contents, in addition to specifying the posision of the element itself. Found a good explanation here:

http://www.w3.org/TR/WD-positioning-970131#Positioned

from section 2.2

Like 'absolute' positioned elements, 'relative'ly positioned define a new coordinate system for child elements, with the origin located in the position where the first child element is rendered

Answer 1

Far as i'm seeing, the corners should be appearing at the top left and right of the page , since your container div doesn't have a CSS position property. Absolute-positioned elements' positions are relative to the innermost parent that has a position other than static (the default).

Try adding position: relative to the container div's CSS. It works much like the default, but (1) if you want, you can shift the div's position by some amount (which isn't extremely useful here, but still), and (2) since the position's not static anymore, absolute-positioned stuff inside the div should position itself relative to the container, rather than to the body/page.

Also, some browsers won't even display a div that has no content -- so the background for said div might not show. You'll probably want to have something in the divs. Even a single   will work.

Answer 2

Have you considered using CSS border-radius to achieve this rather than messing around with images?

border-radius is supported by all browsers except IE, but even IE can be made to work with it with the use of a clever little thing called CSS3Pie .

(plus as a bonus, CSS3Pie also gives IE CSS gradient backgrounds, so you could kill two birds with one stone)