Negative z-index is not rendered correcly
See following example:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>z-index-4.html</title>
<style>
@page {
size: 400pt 400pt;
margin: 100pt;
}
html {
font-size: 8pt;
line-height: 10pt;
margin: 100pt;
}
#lvl_0 {
width: 120pt;
height: 120pt;
position: relative;
background: rgba(255, 0, 0, .8);
}
#lvl_1 {
width: 100pt;
height: 100pt;
position: relative;
z-index: auto;
background: rgba(0, 255, 0, .5);
left:-40pt;
top: -60pt;
}
#lvl-1 {
width: 50pt;
height: 50pt;
position: relative;
background: rgba(0, 0, 255, .5);
right:-80pt;
top: 0;
z-index: -1;
}
#lvl-2 {
width: 50pt;
height: 50pt;
position: relative;
background: rgba(200, 0, 200, 1);
right:-80pt;
bottom: 20pt;
z-index: -2;
}
</style>
</head>
<body>
<div id="lvl_0">
<div id="lvl_1">
<div id="lvl-1"></div>
<div id="lvl-2"></div>
</div>
</div>
</body>
</html>