By combining the grouping of selectors that share the same declaration and declarations that share the same selector you can apply multiple declarations to multiple selectors. This technique allows you to create compact yet powerful CSS rules. This tip combines Group Selectors with Group Declarations into one powerful technique.
So this:
body {font-size: 12px; }
body {font-family: arial, helvetica, sans-serif;}
th {font-size: 12px; font-family: arial, helvetica, sans-serif;}
td {font-size: 12px; font-family: arial, helvetica, sans-serif;}
Becomes this:
body, th, td {font-size: 12px; font-family: arial, helvetica, sans-serif;}
Even better, use shorthand properties to create an optimized CSS rule:
body,th,td{font:12px arial,helvetica,sans-serif;}