列表页原标题写法：

<meta name="keywords" content="<yunu:config name='seo_keywords'>">
<meta name="description" content="<yunu:config name='seo_description'>">
<title>{$category.title}-<yunu:config name="site_title"></title>

20181122更新

上面这种写法在后台栏目设置自定义标题时，是无法显示的，优化写法为

列表页

<title><if condition="strlen($category['seo_title']) neq 0">{$category.seo_title}<else/>{$category.title}-<yunu:config name="site_title"></if></title>
<meta name="keywords" content="<if condition="strlen($category['seo_keywords']) neq 0">{$category.seo_keywords}<else/>{$category.title}</if>">
<meta name="description" content="<if condition="strlen($category['seo_desc']) neq 0">{$category.seo_desc|str2sub=160, true}<else/>{$category.desc|str2sub=160, true}</if>">

这样即可在不填写自定义标题时调用默认标题，填写自定义标题时调用自定义标题

详情页：

<title><if condition="strlen($content['seo_title']) neq 0">{$content.seo_title}<else/>{$content.title}-<yunu:config name="site_title"></if></title>
<meta name="keywords" content="<if condition="strlen($content['seo_keywords']) neq 0">{$content.seo_keywords}<else/>{$content.title}</if>">
<meta name="description" content="<if condition="strlen($content['seo_desc']) neq 0">{$content.seo_desc|str2sub=160, true}<else/>{$content.content|str2sub=160, true} </if>">