set all ggplot font sizes relative to base font size

Change-Id: I31f5740b335001d4d2826266b94746bf9391e820
diff --git a/Changelog.md b/Changelog.md
index cf4395b..5b7a146 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -3,6 +3,7 @@
 ## 0.5.900
 * decrease ggplot2 base_size from 12 to 10
 * set default font for geom_text
+* set all ggplot font sizes relative to base font size
 
 ## 0.4.900
 * decrease ggplot2 base_size from 14 to 12
diff --git a/R/ggplot-theme.R b/R/ggplot-theme.R
index d95daab..67f06c3 100644
--- a/R/ggplot-theme.R
+++ b/R/ggplot-theme.R
@@ -41,20 +41,20 @@
                     "dark" = backgroundColorDark)
 
   ret <- theme(rect = element_rect(fill = bgcolor, linetype = 0, colour = NA),
-               text = element_text(size = base_size, family = base_family),
+               text = element_text(size = base_size * 0.8, family = base_family),
                plot.title = element_text(hjust = 0.5),
-               plot.subtitle = element_text(hjust = 0.5, size = 13, colour = mediumContrastColor),
+               plot.subtitle = element_text(hjust = 0.5, size = base_size * 0.9, colour = mediumContrastColor),
                title = element_text(hjust = 0.5),
-               axis.text = element_text(size = 11, family = base_family),
-               axis.title = element_text(size = 11, family = base_family),
-               legend.text = element_text(size = 11, family = base_family),
-               strip.text =  element_text(size = 11, family = base_family),
-               axis.title.x = element_text(hjust = 0.5, size = 11,
+               axis.text = element_text(size = base_size * 1.0, family = base_family),
+               axis.title = element_text(size = base_size * 1.0, family = base_family),
+               legend.title = element_text(size = base_size * 1.0, family = base_family, colour = mediumContrastColor),
+               legend.text = element_text(size = base_size * 1.0, family = base_family),
+               strip.text =  element_text(size = base_size * 1.0, family = base_family),
+               axis.title.x = element_text(hjust = 0.5, size = base_size * 1.0,
                                            colour = mediumContrastColor),
-               axis.title.y = element_text(hjust = 0.5, size = 11,
+               axis.title.y = element_text(hjust = 0.5, size = base_size * 1.0,
                                            margin = margin(r = 10),
                                            colour = mediumContrastColor),
-               legend.title = element_text(size=11, colour = mediumContrastColor),
                panel.grid.major.x = element_line(linetype = "dotted", colour = lowContrastColor),
                panel.grid.major.y = element_line(colour = lowContrastColor),
                panel.grid.minor.y = element_blank(),
@@ -78,6 +78,7 @@
   }
   update_geom_defaults("text", list(size = 3, family = base_family))
   ret
+
 }