sbox-public/game/addons/menu/Code/MenuUI/Components/GameJamDropdown.razor

@using System;
@using Sandbox;
@using Sandbox.UI;
@using System.Threading

<root class="packagefilterfacet" onmousedown="@OpenMenu">

    <div>@Value</div>

    <div class="addon-button"><i>emoji_events</i></div>

</root>

@code
{
	public string[] GameJams { get; set; }
	public string Value { get; set; }
	public Action<string> OnChange { get; set; }

	Popup menu;

	void SwitchTo( string entry )
	{
		Value = entry;
		OnChange?.Invoke(entry);
		StateHasChanged();
	}

	void OpenMenu()
	{
		if (menu.IsValid())
		{
			menu.Delete();
			return;
		}

		menu = new Popup(this, Popup.PositionMode.BelowLeft, 0.0f);
		menu.Style.Set( "margin-top", "8px" );
		menu.Style.Set( "border", "2px solid #1E2432" );
		menu.Style.Set( "border-radius", "16px" );
		menu.Style.Set( "font-family", "Poppins" );
		menu.Style.Set( "font-size", "14px" );
		menu.Style.Set("background-color", "rgba(#131820, 0.8)");
		menu.Style.Set("backdrop-filter", "blur(4px);");
		menu.StyleSheet.Parse( @"
								Button {
									cursor: pointer;
									align-items: center;

									&:hover{
										sound-in: ui.button.over;
									}

									&:active {
										sound-out: ui.button.press;
									}
								}
							");

        foreach (string entry in GameJams)
        {
            var o = menu.AddOption(entry, "emoji_events", () => SwitchTo(entry));

            if (Value == entry)
            {
                o.AddClass("active");
            }
        }

    }

}