Optimize stylesheet

source/css/_common/components/post/post-gallery.styl

@@ -1,7 +1,7 @@
 .post-gallery {
   align-items: center;
   display: grid;
-  grid-gap: 10px;
+  gap: 10px;
   grid-template-columns: 1fr 1fr 1fr;
   margin-bottom: 20px;
 

source/css/_common/components/third-party/related-posts.styl

@@ -1,6 +1,5 @@
 .popular-posts-header {
   border-bottom: 1px solid $gainsboro;
-  display: block;
   font-size: $font-size-large;
   margin-bottom: 10px;
   margin-top: $post-eof-margin-bottom;

source/css/_common/outline/header/site-nav.styl

@@ -18,10 +18,7 @@
 }
 
 .site-nav {
-  display: block;
-
   +mobile() {
-    clear: both;
     display: none;
   }
 

source/css/_common/outline/sidebar/sidebar-author.styl

@@ -1,22 +1,18 @@
 .site-author-image {
   border: $site-author-image-border-width solid $site-author-image-border-color;
-  display: block;
-  margin: 0 auto;
   max-width: $site-author-image-width;
   padding: 2px;
 
   if (hexo-config('avatar.rounded')) {
     border-radius: 50%;
   }
-}
 
-if (hexo-config('avatar.rotated')) {
-  .site-author-image {
+  if (hexo-config('avatar.rotated')) {
     transition: transform 1s ease-out;
-  }
 
-  .site-author-image:hover {
-    transform: rotateZ(360deg);
+    &:hover {
+      transform: rotateZ(360deg);
+    }
   }
 }
 

source/css/_common/scaffolding/tags/link-grid.styl

@@ -1,6 +1,6 @@
 .post-body .link-grid {
   display: grid;
-  grid-gap: 1.5rem 1.5rem;
+  gap: 1.5rem 1.5rem;
   grid-template-columns: 1fr 1fr;
   padding: 1.5rem;
 

source/css/_common/scaffolding/tags/tabs.styl

@@ -3,9 +3,7 @@
 }
 
 .post-body .tabs, .tabs-comment {
-  display: block;
   padding-top: 10px;
-  position: relative;
 
   ul.nav-tabs {
     display: flex;