diff --git a/static_files/style.css b/static_files/style.css
index 3de7065..2978081 100644
--- a/static_files/style.css
+++ b/static_files/style.css
@@ -24,7 +24,7 @@
 }
 
 .editor {
-    width: 100%;
+    width: calc(100% - 1.25em); /* The width is calculated *inside* the padding, so adjust for it. */
     height: 6eM;
     font-size: large;
     padding: 0.5em;