Merge branch 'dz-fix-issue-sidebar' into 'master'

Fix UI issues caused by header height decrease to 50px

- fix blank spacing for issue sidebar
- fix login btn alignment for non logged in users

See merge request !4143

app/assets/stylesheets/framework/common.scss

@@ -289,7 +289,7 @@ table {
   text-shadow: none;
 
   @media (min-width: $screen-sm-min) {
-    margin-top: 11px;
+    margin-top: 8px;
   }
 }
 

app/assets/stylesheets/framework/header.scss

@@ -6,12 +6,12 @@ header {
   transition-duration: .3s;
 
   &.navbar-empty {
-    height: 58px;
+    height: $header-height;
     background: #fff;
     border-bottom: 1px solid $btn-gray-hover;
 
     .center-logo {
-      margin: 11px 0;
+      margin: 8px 0;
       text-align: center;
 
       #tanuki-logo, img {

app/assets/stylesheets/pages/issuable.scss

@@ -125,7 +125,7 @@
 
 .right-sidebar {
   position: fixed;
-  top: 58px;
+  top: $header-height;
   bottom: 0;
   right: 0;
   z-index: 10;