Fix performance of home feed regeneration (#12084)

Fetching statuses from all followed accounts at once takes too long
within Postgres. Fetching them one by one and merging in Ruby
could be a lot less resource-intensive

Because the query for dynamically fetching the home timeline is so
heavy, we can no longer offer it when the home timeline is missing

app/javascript/styles/mastodon/components.scss

@@ -3127,37 +3127,27 @@ a.status-card.compact:hover {
   cursor: default;
   display: flex;
   flex: 1 1 auto;
+  flex-direction: column;
   align-items: center;
   justify-content: center;
   padding: 20px;
 
-  & > div {
-    width: 100%;
-    background: transparent;
-    padding-top: 0;
-  }
-
   &__figure {
-    background: url('../images/elephant_ui_working.svg') no-repeat center 0;
-    width: 100%;
-    height: 160px;
-    background-size: contain;
-    position: absolute;
-    top: 50%;
-    left: 50%;
-    transform: translate(-50%, -50%);
-  }
-
-  &.missing-indicator {
-    padding-top: 20px + 48px;
-
-    .regeneration-indicator__figure {
-      background-image: url('../images/elephant_ui_disappointed.svg');
+    &,
+    img {
+      display: block;
+      width: auto;
+      height: 160px;
+      margin: 0;
     }
   }
 
+  &--without-header {
+    padding-top: 20px + 48px;
+  }
+
   &__label {
-    margin-top: 200px;
+    margin-top: 30px;
 
     strong {
       display: block;

app/javascript/styles/mastodon/introduction.scss

@@ -3,9 +3,10 @@
   flex-direction: column;
   justify-content: center;
   align-items: center;
+  height: 100vh;
+  background: $ui-base-color;
 
   @media screen and (max-width: 920px) {
-    background: darken($ui-base-color, 8%);
     display: block !important;
   }