Reduce margins around datatables

Change-Id: I2cb72ea08e9f7d5b28ed38ae5332bbec5e8880ae
diff --git a/inst/rmarkdown/templates/posterdown_ids/resources/template.html b/inst/rmarkdown/templates/posterdown_ids/resources/template.html
index 4b779ac..128598c 100644
--- a/inst/rmarkdown/templates/posterdown_ids/resources/template.html
+++ b/inst/rmarkdown/templates/posterdown_ids/resources/template.html
@@ -310,6 +310,10 @@
 }
 }
 
+.poster_body .html-widget {
+    margin-top: 1cm;
+    margin-bottom: 0.5cm;
+}
 
 h1, h2, h3, h4, h5 {
   page-break-after: avoid;