Update style.css

'Header Sytles' typo

library/css/style.css

@@ -758,7 +758,7 @@ and will be used across all viewports.
 03. LAYOUT & GRID STYLES
 04. LINK STYLES
 05. H1, H2, H3, H4, H5 STYLES
-06. HEADER SYTLES
+06. HEADER STYLES
 07. NAVIGATION STYLES
 08. POSTS & CONTENT STYLES
 09. PAGE NAVI STYLES