Adjust styles for comment collapse buttons

Just a few minor style adjustments to simplify the styles and fix some
bad wrapping behavior with the new bulk-collapse/expand buttons.

tildes/scss/modules/_btn.scss

@@ -52,10 +52,8 @@
 
   font-weight: normal;
 
-  border-left-width: 0;
   margin-right: 0.4rem;
   @media (min-width: $size-md) {
-    border-left-width: 1px;
     margin-right: 0.2rem;
     min-width: 0.8rem;
   }
@@ -65,22 +63,6 @@
   }
 }
 
-.btn-comment-collapse-all {
-  margin-left: 0.4rem;
-  border-left-width: 1px;
-  @media (min-width: $size-md) {
-    margin-top: 0.35rem;
-  }
-}
-
-.btn-comment-expand-all {
-  margin-left: 0.2rem;
-  border-left-width: 1px;
-  @media (min-width: $size-md) {
-    margin-top: 0.35rem;
-  }
-}
-
 .btn-comment-tag {
   display: inline-flex;
   align-items: center;

tildes/scss/modules/_topic.scss

@@ -248,8 +248,14 @@
 .topic-comments {
   header {
     display: flex;
+    flex-wrap: wrap;
+    align-items: center;
+
+    margin-bottom: 0.4rem;
 
     h2 {
+      margin-bottom: 0;
+      margin-right: 0.4rem;
       white-space: nowrap;
     }
 

tildes/tildes/templates/topic.jinja2

@@ -153,8 +153,8 @@
       {% endtrans %}
       </h2>
 
-      <button class="btn btn-comment-collapse btn-comment-collapse-all" data-js-comment-collapse-all-button title="Collapse child comments">&minus;</button>
-      <button class="btn btn-comment-collapse btn-comment-expand-all" data-js-comment-expand-all-button title="Expand all comments">+</button>
+      <button class="btn btn-comment-collapse" title="Collapse reply comments" data-js-comment-collapse-all-button>&minus;</button>
+      <button class="btn btn-comment-collapse" title="Expand all comments" data-js-comment-expand-all-button>+</button>
 
       <form class="form-listing-options" method="get">
         <div class="form-group">