In SAS 9.1.3, when the ASIS=ON is requested in a STYLE option, all the other STYLE attributes for that variable are ignored. This happens only in the ODS HTML destination.
A workaround would be to use a format with in-line formatting containing the desired style attributes.
For example:
proc format;
value $indent
'F' = '|S={leftmargin=.5cm}my text|S={}';
run;
ods escapechar = '|';
ods html file = 'myfile.htm';
proc report data=sashelp.class nowd;
define age / format=$indent.;
run;
ods html close;