In "header", "footer" and "spacer_open" templates find this:
Code:
width="$stylevar[outertablewidth]"
and replace with this:
Code:
style="width: $stylevar[outertablewidth]; margin 0 auto;"
and add "px" back.
In spacer_open you'll also find this:
Code:
<div class="page" style="width:$stylevar[outerdivwidth]; text-align:$stylevar[left]">
replace that line with this:
Code:
<div class="page" style="width:$stylevar[outerdivwidth]; margin 0 auto; text-align:$stylevar[left]">