Remove some unneeded uses of @extend.

assets/sass/components/responsive-video/_responsive-video.scss

@@ -16,10 +16,7 @@ default 16:9 one. */
   padding-block-start: 25px; /* Height of video controls */
   height: 0;
 
-  iframe {
-    @extend %responsive-video__embed;
-  }
-
+  iframe,
   &__embed {
     position: absolute;
     inset-block-start: 0;

assets/sass/components/tags/_tags.scss

@@ -1,7 +1,5 @@
 .tags {
   ul {
-    @extend %flex-inline;
-    @extend %flex-inline--inline;
     margin-block: 0;
   }
 }

layouts/_partials/tags.html

@@ -1,6 +1,6 @@
 <div class="tags meta">
 {{ i18n "taxo_tags" }}:
-<ul>
+<ul class="flex-inline flex-inline--inline">
 {{ range (.GetTerms "tags") -}}
 <li><a href="{{ .RelPermalink }}">{{ .LinkTitle }}</a></li>
 {{ end -}}