Fix Markdown preview style

However styles in markdown-body affect tab. So there are invalid margin at the top of the tab.

src/main/scala/gitbucket/core/controller/RepositoryViewerController.scala

@@ -111,6 +111,7 @@ trait RepositoryViewerControllerBase extends ControllerBase {
       enableRefsLink = params("enableRefsLink").toBoolean,
       enableLineBreaks = params("enableLineBreaks").toBoolean,
       enableTaskList = params("enableTaskList").toBoolean,
+      enableAnchor = false,
       hasWritePermission = hasWritePermission(repository.owner, repository.name, context.loginAccount)
     )
   })

src/main/scala/gitbucket/core/view/Markdown.scala

@@ -39,22 +39,28 @@ object Markdown {
     } else markdown
 
     // escape task list
-    val source = if(enableTaskList){
-      escapeTaskList(s)
-    } else s
+    val source = if(enableTaskList) escapeTaskList(s) else s
 
     val options = new Options()
     options.setSanitize(true)
     options.setBreaks(enableLineBreaks)
-    val renderer = new GitBucketMarkedRenderer(options, repository, enableWikiLink, enableRefsLink, enableAnchor, enableTaskList, hasWritePermission, pages)
+
+    val renderer = new GitBucketMarkedRenderer(options, repository,
+      enableWikiLink, enableRefsLink, enableAnchor, enableTaskList, hasWritePermission, pages)
+
     Marked.marked(source, options, renderer)
   }
 
   /**
    * Extends markedj Renderer for GitBucket
    */
-  class GitBucketMarkedRenderer(options: Options, repository: RepositoryService.RepositoryInfo,
-                                enableWikiLink: Boolean, enableRefsLink: Boolean, enableAnchor: Boolean, enableTaskList: Boolean, hasWritePermission: Boolean,
+  class GitBucketMarkedRenderer(options: Options,
+                                repository: RepositoryService.RepositoryInfo,
+                                enableWikiLink: Boolean,
+                                enableRefsLink: Boolean,
+                                enableAnchor: Boolean,
+                                enableTaskList: Boolean,
+                                hasWritePermission: Boolean,
                                 pages: List[String])
                                (implicit val context: Context) extends Renderer(options) with LinkConverter with RequestCache {
 
@@ -62,11 +68,14 @@ object Markdown {
       val id = generateAnchorName(text)
       val out = new StringBuilder()
 
-      out.append("<h" + level + " id=\"" + options.getHeaderPrefix + id + "\" class=\"markdown-head\">")
+      out.append("<h" + level + " id=\"" + options.getHeaderPrefix + id + "\"")
 
       if(enableAnchor){
+        out.append(" class=\"markdown-head\">")
         out.append("<a class=\"markdown-anchor-link\" href=\"#" + id + "\"></a>")
         out.append("<a class=\"markdown-anchor\" name=\"" + id + "\"></a>")
+      } else {
+        out.append(">")
       }
 
       out.append(text)
@@ -83,22 +92,21 @@ object Markdown {
       var listType: String = null
       if (ordered) {
         listType = "ol"
-      }
-      else {
+      } else {
         listType = "ul"
       }
       if(body.contains("""class="task-list-item-checkbox"""")){
-        return "<" + listType + " class=\"task-list\">\n" + body + "</" + listType + ">\n"
+        "<" + listType + " class=\"task-list\">\n" + body + "</" + listType + ">\n"
       } else {
-        return "<" + listType + ">\n" + body + "</" + listType + ">\n"
+        "<" + listType + ">\n" + body + "</" + listType + ">\n"
       }
     }
 
     override def listitem(text: String): String = {
       if(text.contains("""class="task-list-item-checkbox" """)){
-        return "<li class=\"task-list-item\">" + text + "</li>\n"
+        "<li class=\"task-list-item\">" + text + "</li>\n"
       } else {
-        return "<li>" + text + "</li>\n"
+        "<li>" + text + "</li>\n"
       }
     }
 

src/main/scala/gitbucket/core/view/helpers.scala

@@ -89,6 +89,7 @@ object helpers extends AvatarImageProvider with LinkConverter with RequestCache
                enableWikiLink: Boolean,
                enableRefsLink: Boolean,
                enableLineBreaks: Boolean,
+               enableAnchor: Boolean = true,
                enableTaskList: Boolean = false,
                hasWritePermission: Boolean = false,
                pages: List[String] = Nil)(implicit context: Context): Html =
@@ -97,7 +98,7 @@ object helpers extends AvatarImageProvider with LinkConverter with RequestCache
       repository         = repository,
       enableWikiLink     = enableWikiLink,
       enableRefsLink     = enableRefsLink,
-      enableAnchor       = true,
+      enableAnchor       = enableAnchor,
       enableLineBreaks   = enableLineBreaks,
       enableTaskList     = enableTaskList,
       hasWritePermission = hasWritePermission,

src/main/webapp/assets/common/css/gitbucket.css

@@ -1718,28 +1718,34 @@ div.markdown-body h1 {
   border-bottom: 1px solid #ddd;
   font-size: 2.5em;
   font-weight: bold;
+  line-height: 1.7;
 }
 
 div.markdown-body h2 {
   border-bottom: 1px solid #eee;
   font-size: 2em;
+  line-height: 1.7;
 }
 
 div.markdown-body h3 {
   font-size: 1.5em;
+  line-height: 1.7;
 }
 
 div.markdown-body h4 {
   font-size: 1.2em;
+  line-height: 1.7;
 }
 
 div.markdown-body h5 {
   font-size: 1em;
+  line-height: 1.7;
 }
 
 div.markdown-body h6 {
   color:#777;
   font-size: 1em;
+  line-height: 1.7;
 }
 
 div.markdown-body li {
@@ -1905,7 +1911,6 @@ div.markdown-body table colgroup + tbody tr:first-child td:last-child {
 
 .markdown-head {
   position: relative;
-  line-height: 1.7;
 }
 
 a.markdown-anchor-link {