diff --git a/app/assets/javascripts/highlightTags.js b/app/assets/javascripts/highlightTags.js
index 472d479c7..f0f46fcd9 100644
--- a/app/assets/javascripts/highlightTags.js
+++ b/app/assets/javascripts/highlightTags.js
@@ -23,6 +23,10 @@
         .on("input", this.update)
         .on("scroll", this.maintainScrollParity);
 
+      this.$backgroundMaskForeground.width(
+        this.$textbox.width()
+      );
+
       this.$textbox
         .trigger("input");
 
diff --git a/app/assets/stylesheets/components/textbox.scss b/app/assets/stylesheets/components/textbox.scss
index 224750586..a17aed6fd 100644
--- a/app/assets/stylesheets/components/textbox.scss
+++ b/app/assets/stylesheets/components/textbox.scss
@@ -18,11 +18,10 @@
     display: block;
     box-sizing: border-box;
     position: relative;
-    width: 500px;
-    height: 200px;
     margin: 0;
     padding: 4px;
     overflow: hidden;
+    height: 200px;
   }
 
   &-background,