Destacar la primera etiqueta, entradas de blogger

firstag-tag.css

.firstag {
   position: relative;
   display: block;
}
.firstag-name {
   position: absolute;
   top: .5rem;
   right: .5rem;
   padding: .2rem .5rem;
   background-color: #00BCD4;
   color: #fff;
   border-radius: 3px;
   z-index: 20;
   text-transform: capitalize;
}
.firstag-name--anime {
   background-color: #8BC34A;
}
.firstag-name--manga {
   background-color: #3F51B5;
}
.firstag-name--ova {
   background-color: #FF9800;
}

firstag-tag.xml

<!-- No olvidar que el contenedor necesita la clase "firstag" de la siguiente forma:
<div class='firstag'>
{{xml:contenido}}
</div>
-->

<!-- Condicion Lambda -->
<b:loop values='data:post.labels first (tag => tag.name in {"anime","manga","ova"})' var='label'>
   <span expr:class='"firstag-name firstag-name--" + data:label.name'><data:label.name/></span>
</b:loop>