diff --git a/src/assets/stylesheets/helpers/_px2em.scss b/src/assets/stylesheets/helpers/_px2em.scss
index da40340cc..0756797c4 100644
--- a/src/assets/stylesheets/helpers/_px2em.scss
+++ b/src/assets/stylesheets/helpers/_px2em.scss
@@ -35,9 +35,13 @@
 ///
 @function px2em($size, $base: 16px) {
   @if unit($size) == px {
-    @return ($size / $base) * 1.0em;
+    @if unit($base) == px {
+      @return ($size / $base) * 1.0em;
+    } @else {
+      @error "Invalid base: #{$base} - unit must be 'px'";
+    }
   } @else {
-    @error "Invalid unit: #{$size} - must be px";
+    @error "Invalid size: #{$size} - unit must be 'px'";
   }
 }
 
@@ -52,8 +56,12 @@
 ///
 @function px2rem($size, $base: 10px) {
   @if unit($size) == px {
-    @return ($size / $base) * 1.0rem;
+    @if unit($base) == px {
+      @return ($size / $base) * 1.0rem;
+    } @else {
+      @error "Invalid base: #{$base} - unit must be 'px'";
+    }
   } @else {
-    @error "Invalid unit: #{$size} - must be px";
+    @error "Invalid size: #{$size} - unit must be 'px'";
   }
 }
diff --git a/src/assets/stylesheets/themes/_default.scss b/src/assets/stylesheets/themes/_default.scss
deleted file mode 100644
index a64631714..000000000
--- a/src/assets/stylesheets/themes/_default.scss
+++ /dev/null
@@ -1,12 +0,0 @@
-// ----------------------------------------------------------------------------
-// Theme colors
-// ----------------------------------------------------------------------------
-
-// Headlines
-// $md-theme-h1-color:        $md-color-black--light;
-// $md-theme-h2-color:        $md-color-black;
-// $md-theme-h3-color:        $md-color-black;
-// $md-theme-h4-color:        $md-color-black;
-// $md-theme-h5-6-color:      $md-color-black--light;
-//
-// $md-theme-hr-color:        $md-color-black--lighter;