add author_textcol to posterdown_betterport template, similar to #110
diff --git a/inst/rmarkdown/templates/posterdown_betterport/resources/template.html b/inst/rmarkdown/templates/posterdown_betterport/resources/template.html
index e27de61..da34ac1 100644
--- a/inst/rmarkdown/templates/posterdown_betterport/resources/template.html
+++ b/inst/rmarkdown/templates/posterdown_betterport/resources/template.html
@@ -178,7 +178,7 @@
 background: 0;
 }
 #author {
-color: $if(primary_colour)$$primary_colour$$else$#0b4545$endif$;
+color:$if(author_textcol)$$author_textcol$$else$$if(primary_colour)$$primary_colour$$else$#0b4545$endif$$endif$;
 margin: 0;
 line-height: 85%;
 font-size: $if(author_textsize)$$author_textsize$$else$1.17em$endif$;