Revert "fix for cutted select2 in timeline view"

This causes regressions (large whitespace areas) in various views,
including the classic work packages page.

This reverts commit 5dea05c2a6.

app/assets/stylesheets/layout/_base.sass

@@ -77,14 +77,10 @@ body
   margin: 0 0 0 $main-menu-width
   padding: 10px 20px
   width: auto
+  overflow: hidden
   height: auto
   background-color: #fff
   z-index: 10
-  .clearfix
-    &:before,
-    &:after
-      display: initial
-      clear: none
 
   %absolute-layout-mode &
     position:   absolute