Index: util/relativize
==================================================================
--- util/relativize
+++ util/relativize
@@ -21,13 +21,14 @@
     echo "[$(date +'%Y-%m-%dT%H:%M:%S%z')]: ${base_dir} not a directory!" >&2
     exit 1
 fi
 
 # Root folder: remove leading / from href and src attributes
-sed -i '' -- 's/href=\"\//href=\"/g' "${base_dir}"*.html
-sed -i '' -- 's/src=\"\//src=\"/g' "${base_dir}"*.html
+# Works across (and preserves) line breaks introduced by the `tidy` command
+perl -0777 -i -pe 's/ href=(\s*)"\// href=$1"/ig' "${base_dir}"*.html
+perl -0777 -i -pe 's/ src=(\s*)"\// src=$1"/ig' "${base_dir}"*.html
 
 # subfolders: replace leading / with ../ in href and src attributes
-sed -i '' -- 's/href=\"\//href=\"..\//g' "${base_dir}"articles/*.html
-sed -i '' -- 's/src=\"\//src=\"..\//g' "${base_dir}"articles/*.html
-sed -i '' -- 's/href=\"\//href=\"..\//g' "${base_dir}"series/*.html
-sed -i '' -- 's/src=\"\//src=\"..\//g' "${base_dir}"series/*.html
+perl -0777 -i -pe 's/ href=(\s*)"\// href=$1"..\//ig' "${base_dir}"articles/*.html
+perl -0777 -i -pe 's/ src=(\s*)"\// src=$1"..\//ig' "${base_dir}"articles/*.html
+perl -0777 -i -pe 's/ href=(\s*)"\// href=$1"..\//ig' "${base_dir}"series/*.html
+perl -0777 -i -pe 's/ src=(\s*)"\// src=$1"..\//ig' "${base_dir}"series/*.html