position:absolute

[MudGuard]

Hi,

es gibt keinen negativen z-index

Also das sehe ich anders.
z-index ist definiert als (siehe http://www.w3.org/TR/REC-CSS2/visuren.html#propdef-z-index)

'z-index'
    Value:   auto | <integer> | inherit
    Initial:   auto
    Applies to:   positioned elements
    Inherited:   no
    Percentages:   N/A
    Media:   visual

For a positioned box, the 'z-index' property specifies:

1. The stack level of the box in the current stacking context.
   2. Whether the box establishes a local stacking context.

Values have the following meanings:

<integer>
    This integer is the stack level of the generated box in the current stacking context. The box also establishes a local stacking context in which its stack level is '0'.
auto
    The stack level of the generated box in the current stacking context is the same as its parent's box. The box does not establish a new local stacking context.

Hier gibt es also keine Einschränkung für integer-Werte.

Also muß noch bei <integer> (http://www.w3.org/TR/REC-CSS2/syndata.html#value-def-integer) nachgeguckt werden. Da steht:

4.3.1 Integers and real numbers

Some value types may have integer values (denoted by <integer>) or real number values (denoted by <number>). Real numbers and integers are specified in decimal notation only. An <integer> consists of one or more digits "0" to "9". A <number> can either be an <integer>, or it can be zero or more digits followed by a dot (.) followed by one or more digits. Both integers and real numbers may be preceded by a "-" or "+" to indicate the sign.

Note that many properties that allow an integer or real number as a value actually restrict the value to some range, often to a non-negative value.

Hier wird also grundsätzlich erlaubt, auch negative Werte anzugeben - Abweichungen davon wären bei der jeweiligen Eigenschaft definiert.
Gibt es aber nicht, s.o. ==> negative z-index Werte sind erlaubt.

cu,
Andreas