Single Product Price Size

.summary .price {font-size: 26px;}

Theme markup varies, so if this doesn’t work for you, please post the url to a relevant page.

Thanks Lorro, but that didn’t seem to work. Have a look:
https://nuu-muu.com/temp/product/samba-ruu/

Your theme needs it a bit different:

.entry-summary p.price span {
  font-size: 16px!important;
}

Nailed it, thank you!!!