updates theme.r for tidyverse#1565

Author: Katiedaisey

R/theme-defaults.r

@@ -230,8 +230,8 @@ theme_classic <- function(base_size = 12, base_family = ""){
     theme(
       panel.border     = element_blank(),
       axis.line        = element_line(colour = "black"),
-      panel.grid.major   = element_line(),
-      panel.grid.minor   = element_line(),
+      panel.grid.major = element_blank(),
+      panel.grid.minor = element_blank(),
       strip.background = element_rect(colour = "black", size = 0.5),
       legend.key       = element_blank()
     )