How can I change the compare to price color on Venture theme?

Store Design
10

@gadjetsgalore – there you go …

/* product details */
.product-single__price--compare.product-single__price--compare {
  color: #666;
}
.product-single__price.product-single__price {
  color: #f00;
}

/* card */
.product-card__regular-price.product-card__regular-price {
  color: #666;
}
.product-card__price.product-card__price {
  color: #f00;
}

However, the regular price will ALWAYS be red, not just for the items on sale. If you want that changed, the theme needs to be modified a little.

Hope this helps,
Mario