Flexify the contest dashboard

app/views/contests/show.html.slim

@@ -28,8 +28,8 @@ javascript:
       </svg>
       =< t("contests.show.copy_extension_url")
     
-.row.mb-4
-  .col-7
+.row.mb-4 style="height: calc(100vh - 320px)"
+  .col-7.d-flex.flex-column style="height: 100%"
     .row
       .col
         h4
@@ -65,6 +65,7 @@ javascript:
         .row
           .col.alert.alert-danger
             = t("messages.warning")
+      .d-flex.flex-column style="overflow-y: auto"
         table.table.table-striped.table-hover
           thead
             tr
@@ -101,7 +102,7 @@ javascript:
                       = t("helpers.buttons.add_completion")
                 td
                   = link_to t("helpers.buttons.delete"), contest_message_path(@contest, message), data: { turbo_method: :delete }, class: "btn btn-sm btn-danger"
-  .col-5
+  .col-5.d-flex.flex-column style="height: 100%"
     .row
       .col
         h4
@@ -110,6 +111,7 @@ javascript:
             | + #{t("helpers.buttons.add")}
           a.ms-3.btn-sm.btn.btn-primary href=contest_import_path(@contest) style="margin-top: -3px"
             | #{t("helpers.buttons.import")}
+    .d-flex.flex-column style="overflow-y: auto"
       table.table.table-striped.table-hover
         thead
           tr