Possible workarounds:

-set display: inline-block to the control wrapper -.RadColorPicker {display: inline-block;}

- use Classic RenderMode

- improve the z-index and backgrounds of the anchor:

		div.RadColorPicker.lwr div.rcpIcon a,
		div.RadColorPicker.lwr div.rcpIcon a:hover
		{
			z-index: 11;
			background-color: transparent;
			background-image: none;
		}

where the lwr class is to be added from the server code to avoid breaking the Classic render mode:

	protected void Page_Load(object sender, EventArgs e)
	{
		if (RadColorPicker1.RenderMode == Telerik.Web.UI.RenderMode.Lightweight)
		{
			RadColorPicker1.CssClass = "lwr";
		}
	}