Use Cascading Parameter to provide server component with selected city parameter to set a background color.

ServerManagement/Components/Controls/ServerComponent.razor

@@ -4,7 +4,7 @@
 
 @if (Server != null)
 {
-  <li @key="Server.Id">
+  <li @key="Server.Id" style="background-color: @GetBackgroundColor();">
     @Server.Name in @Server.City is
     <span style="color:@(Server.IsOnline ? "green" : "red")">
       @(Server.IsOnline ? "online" : "offline")
@@ -51,6 +51,9 @@
   [Parameter]
   public Server? Server { get; set; }
 
+  [CascadingParameter(Name="SelectedCity")]
+  public string? SelectedCity { get; set; }
+
   private void DeleteServer(int serverId)
   {
     if (serverId > 0)
@@ -59,4 +62,24 @@
       NavigationManager.Refresh(forceReload: true);
     }
   }
+
+  private string GetBackgroundColor()
+  {
+    if (SelectedCity != null) {
+      switch (this.SelectedCity)
+      {
+        case "Eindhoven": return "lightskyblue";
+        case "Helmond": return "lightcoral";
+        case "Oosterhout": return "lightgreen";
+        case "Roosendaal": return "lightsalmon";
+        case "Deurne": return "lightpink";
+        default:
+          return "white";
+      }
+    }
+    else
+    {
+      return "white";
+    }
+  }
 }

ServerManagement/Components/Pages/Servers.razor

@@ -11,11 +11,12 @@
 <a href="@($"/servers/add")" class="btn btn-primary">Add</a>
 <br/>
 
-<ServerListComponent
-  CityName="@this.selectedCity"
-  SearchFilter="@this.searchFilter">
-
-</ServerListComponent>
+<CascadingValue Name="SelectedCity" Value="@selectedCity">
+  <ServerListComponent
+    CityName="@this.selectedCity"
+    SearchFilter="@this.searchFilter">
+  </ServerListComponent>
+</CascadingValue>
 
 @code {
   private string selectedCity = "Eindhoven";