Blogger: implementing with IF condition with data:blog.homepageUrl

In my blogger template I have the following code:

<b:if cond='data:blog.url == data:blog.homepageUrl + "search/label/BLOG"'>
    <style type="text/css">
      body {
        width: 100%;
        height: 100vh;
        background-color: #CCFF99;
        background-position: center center;
        background-size: cover;
        background-repeat: no-repeat;
        background-attachment: fixed;
      }
    </style>
    <b:else />
    <style type="text/css">
      body {
        width: 100%;
        height: 100vh;
        background-color: #FFFFCD;
        background-position: center center;
        background-size: cover;
        background-repeat: no-repeat;
        background-attachment: fixed;
      }
    </style>
  </b:if>

but,it is not work,how to fix?

<b:if cond='data:blog.url == data:blog.homepageUrl + "search/label/CSS"'>

not work. Anyway, knowing how to do is a good thing to furure cases.