[Glitch] Enhance dashboard styles

Port b58d32cfe2 to glitch-soc

Signed-off-by: Claire <claire.github-309c@sitedethib.com>

app/javascript/flavours/glitch/styles/admin.scss

@@ -936,6 +936,13 @@ a.name-tag,
 }
 
 .retention {
+  overflow: auto;
+
+  > h4 {
+    position: sticky;
+    left: 0;
+  }
+
   &__table {
     &__number {
       color: $secondary-text-color;
@@ -1034,6 +1041,7 @@ a.name-tag,
   &__graph {
     position: absolute;
     bottom: 0;
+    width: 100%;
 
     svg {
       display: block;