Normalise wp table header, details pane tab height

Signed-off-by: Alex Coles <alex@alexbcoles.com>

app/assets/stylesheets/content/_work_packages.sass

@@ -344,13 +344,16 @@ i
   position: relative
   width: 100%
 
+$work-package-details--tab-height: 40px
+
 .tabrow
+  box-sizing: border-box
   text-align: left
   list-style: none
   margin: 0 0 0 10px
-  padding: 4px 0 15px 0
-  line-height: 41px
-  height: 45px
+  padding:     4px 0 0 0
+  line-height: $work-package-details--tab-height - 6px
+  height:      $work-package-details--tab-height
   overflow: hidden
   font-size: 14px
   position: relative

app/assets/stylesheets/content/_work_packages_table.sass

@@ -32,7 +32,7 @@
   to
     opacity: 0
 
-$work-packages-table--header-height: 34px
+$work-packages-table--header-height: 40px
 
 .work-packages-table--container
   position:     relative