.formula
   {
    font-family: "Times New Roman", Times, serif;
    font-style: italic;
   }
.formula_sub
   {
    font-family: "Times New Roman", Times, serif;
    vertical-align: sub;
    font-size: smaller
   }
.cod {  font-family: "Courier New", Courier, mono; text-transform: uppercase}
.formula_sup { font-family: "Times New Roman", Times, serif; vertical-align: super; font-size: smaller }