Fix graph pagination (#15225)

* Fixed invalid HTML tag.

* Fixed pagination.

* Update templates/repo/graph/commits.tmpl

Co-authored-by: zeripath <art27@cantab.net>

Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>
Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

templates/repo/graph/commits.tmpl

@@ -1,9 +1,9 @@
 <div id="rev-container">
 	<ul id="rev-list">
 		{{ range $commitI, $commit := .Graph.Commits }}
-			<li id="commit-{{$commit.Rev}}" data-flow="{{$commit.Flow}}">
+			<li {{if $commit.Rev}}id="commit-{{$commit.Rev}}"{{end}} data-flow="{{$commit.Flow}}">
 				{{ if $commit.OnlyRelation }}
-					<span />
+					<span></span>
 				{{ else }}
 					<span class="sha" id="{{$commit.ShortRev}}">
 						{{$class := "ui sha label"}}

web_src/less/features/gitgraph.less

@@ -1,6 +1,4 @@
 #git-graph-container {
-  float: left;
-  display: block;
   overflow-x: scroll;
   width: 100%;
   min-height: 350px;