frontend: fix several small issues with displaying data tree
diff --git a/frontend-assets/icons/tree_branch.svg b/frontend-assets/icons/tree_branch.svg
index f45dea6..7c55d05 100644
--- a/frontend-assets/icons/tree_branch.svg
+++ b/frontend-assets/icons/tree_branch.svg
@@ -12,9 +12,8 @@
    version="1.1"
    id="svg2"
    inkscape:version="0.91+devel r14491"
-   width="32"
-   height="32"
    viewBox="0 0 32 32"
+   preserveAspectRatio="none"
    sodipodi:docname="tree_branch.svg">
   <metadata
      id="metadata8">