diff --git a/core.css b/core.css
index 6b00018..549ca6e 100644
--- a/core.css
+++ b/core.css
@@ -1,3 +1,6 @@
+html {
+  height: 100%;
+}
 body {
   font-family: Hack, Menlo, Monaco, Ubuntu Mono, monospace;
   font-size: 14px;
@@ -223,4 +226,4 @@ pre>code {
   src: url('fonts/hack-bolditalic.woff2?sha=e700a30') format('woff2'), url('fonts/hack-bolditalic.woff?sha=e700a30') format('woff');
   font-weight: 700;
   font-style: italic;
-}
\ No newline at end of file
+}