Here is a code snippet for this task

.single-product-content .cart .button {
	background-color: #338dd2;
    border-color: #338dd2;
}

.single-product-content .cart .button:hover,
.single-product-content .cart .button:focus {
	background-color: #1d6fad;
    border-color: #1d6fad;
}

.woocommerce-message .button {
	background-color: #338dd2;
    border-color: #338dd2;
}

.woocommerce-message .button:hover,
.woocommerce-message .button:focus {
	background-color: #1d6fad;
    border-color: #1d6fad;
}

.woocommerce-message, 
.wpcf7-mail-sent-ok,
.wishlist_table tr td.product-stock-status span.wishlist-in-stock {
  border-color: #338dd2;
  color:#338dd2;
}