Fix Staking dapp dark mode styles

CHANGELOG.md

@@ -1,7 +1,7 @@
 ## Current
 
 ### Features
-- [#2292](https://github.com/poanetwork/blockscout/pull/2292), [#3356](https://github.com/poanetwork/blockscout/pull/3356), [#3359](https://github.com/poanetwork/blockscout/pull/3359), [#3360](https://github.com/poanetwork/blockscout/pull/3360) - Add Web UI for POSDAO Staking DApp
+- [#2292](https://github.com/poanetwork/blockscout/pull/2292), [#3356](https://github.com/poanetwork/blockscout/pull/3356), [#3359](https://github.com/poanetwork/blockscout/pull/3359), [#3360](https://github.com/poanetwork/blockscout/pull/3360), [#3365](https://github.com/poanetwork/blockscout/pull/3365) - Add Web UI for POSDAO Staking DApp
 - [#3354](https://github.com/poanetwork/blockscout/pull/3354) - Tx hash in EOA coin balance history
 - [#3333](https://github.com/poanetwork/blockscout/pull/3333), [#3337](https://github.com/poanetwork/blockscout/pull/3337) - Dark forest contract custom theme
 - [#3330](https://github.com/poanetwork/blockscout/pull/3330) - Caching of address transactions counter, remove query 10_000 rows limit

apps/block_scout_web/assets/css/theme/_dark-theme.scss

@@ -1046,6 +1046,11 @@ $dark-stakes-banned-background: #3e314c;
 	.tooltip-inversed-color.bs-tooltip-auto[x-placement^="left"] .arrow::before {
 		border-left-color: $btn-line-color !important;
 	}
+
+	.stakes-top {
+		background-color: $dark-bg;
+		background-image: none;
+	}
 }
 
 .navbar-dark .navbar-toggler {

apps/block_scout_web/lib/block_scout_web/controllers/stakes_controller.ex

@@ -38,11 +38,13 @@ defmodule BlockScoutWeb.StakesController do
         })
       end
 
+    epoch_end_in = if epoch_end_block - block_number >= 0, do: epoch_end_block - block_number, else: 0
+
     View.render_to_string(StakesView, "_stakes_top.html",
       account: account,
       block_number: block_number,
       candidates_limit_reached: active_pools_length >= max_candidates,
-      epoch_end_in: epoch_end_block - block_number,
+      epoch_end_in: epoch_end_in,
       epoch_number: epoch_number,
       token: token
     )