Fix margin between compose warning, reply indicator and textarea (#7701)

app/javascript/styles/mastodon/components.scss

@@ -251,7 +251,7 @@
 
   .compose-form__warning {
     color: $inverted-text-color;
-    margin-bottom: 15px;
+    margin-bottom: 10px;
     background: $ui-primary-color;
     box-shadow: 0 2px 6px rgba($base-shadow-color, 0.3);
     padding: 8px 10px;
@@ -583,8 +583,7 @@
 
 .reply-indicator {
   border-radius: 4px;
-  position: relative;
-  bottom: 10px;
+  margin-bottom: 10px;
   background: $ui-primary-color;
   padding: 10px;
 }