Any ideas why <strong> tag doesn't work but CSS does?

If there is nothing else for strong, then there's your problem (or rather, the CSS reset's problem).

The font: inherit style, together with all those selectors, is asking everything to inherit every font style from its parent. The default weight is, obviously, normal, so strong text is no longer bold until you redeclare it:

strong { font-weight: bold; }

(Some other obvious elements to reset styles for are b, em, i, code elements, quote elements, tables, headings, lists, etc.)

add:

strong{
 font-weight:bold;
}

to your CSS. Maybe somewhere you reset this tag.