Revert the CSS sticky fix as it breaks on pages that are smaller than 100% of the viewport height

Author: LukeTowers

modules/backend/assets/css/winter.css

@@ -577,7 +577,7 @@ body.loading,
 body.loading * {cursor:wait !important}
 body.no-select {-webkit-user-select:none;-moz-user-select:none;-ms-user-select:none;user-select:none;cursor:default !important}
 html,
-body {min-height:100%}
+body {height:100%}
 body {font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji","Segoe UI Symbol";background:#f9f9f9;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale}
 #layout-canvas {min-height:100%;height:100%}
 .control-tabs.primary-tabs >ul.nav-tabs,