feat: fix the error page

templates/status/404.tmpl

@@ -1,6 +1,6 @@
 {{template "base/head" .}}
 {{if .IsRepo}}<div class="repository">{{template "repo/header" .}}</div>{{end}}
-<div class="ui container center" style="background:url({{StaticUrlPrefix}}/img/404.png) no-repeat center center fixed;margin-bottom:-80px;height: 100%;width:100%;overflow: hidden;background-size: cover;">
+<div class="ui container center" style="background:url({{StaticUrlPrefix}}/img/404.png) no-repeat center center fixed;margin-bottom:-80px;height: 100%;width:100%;overflow: hidden;background-size: cover;margin:0!important">
 	<div style="height:100%;color:white">
 		<div style="padding-top: 50vh">
 			<div class="ui divider"></div>

templates/status/500.tmpl

@@ -1,6 +1,6 @@
 {{template "base/head" .}}
 {{if .IsRepo}}<div class="repository">{{template "repo/header" .}}</div>{{end}}
-<div class="ui container center" style="background:url({{StaticUrlPrefix}}/img/500.png) no-repeat center center fixed;margin-bottom:-80px;height: 100%;width:100%;overflow: hidden;background-size: cover;">
+<div class="ui container center" style="background:url({{StaticUrlPrefix}}/img/500.png) no-repeat center center fixed;margin-bottom:-80px;height: 100%;width:100%;overflow: hidden;background-size: cover;margin:0!important">
 	<div style="height:100%;color:white">
 		<h1 style="padding-top: 100px;font-size: 180px;color: white;text-align: center;text-shadow: 1px 20px 2px #666;
 			letter-spacing: 20px;">