PLT-7323/PLT-7334 CSS fixes (#7155)

* PLT-7334 - Channel header cuts off list

* PLT-7323 - Fixing alignment for attachments

* PLT-7323 - Fixing close button for attachments

* Changed header description to use margin instead of padding

webapp/sass/layout/_headers.scss

@@ -175,9 +175,10 @@
     }
 
     .channel-header__description {
-        height: 35px;
+        height: 19px;
+        margin-top: 3px;
+        margin-bottom: 13px;
         overflow: hidden;
-        padding: 3px 0 0;
         position: relative;
         text-overflow: ellipsis;
         width: calc(100% - 18px);

webapp/sass/layout/_webhooks.scss

@@ -37,6 +37,16 @@
 }
 
 .post {
+    &.post--comment {
+        .attachment {
+            .attachment__body__wrap {
+                .btn-close {
+                    left: -11px;
+                }
+            }
+        }
+    }
+
     .attachment {
         margin-left: -20px;
         position: relative;
@@ -64,7 +74,7 @@
         .attachment__thumb-pretext {
             background: transparent;
             border: none;
-            margin-left: 5px;
+            margin-left: 25px;
         }
 
         .attachment__container {