Merge pull request #251 from springload/fix/header_cover_section_in_demo

fix: header and footer cover section in demo site

Author: yuzima

demo/src/main.css

@@ -87,8 +87,10 @@ header {
 }
 
 section {
+    position: relative;
     display: flex;
     justify-content: flex-end;
+    z-index: 10;
 }
 
 footer {