How to get different background image for each category added.

Hi ,

I am displaying categories on my homepage. The current theme provides you with the fixed greyish background when each category is added, i have got 16-20 categories and i want different background image for each category , Below is the razor snippet used to display the categories on the hompage:
@model IList<CategoryModel>

@using Nop.Web.Framework.UI;
@using Nop.Web.Models.Catalog;
@if (Model.Count > 0)
{
    <div class="home-page-category-grid">
        @(Html.DataList<CategoryModel>(Model, 5,
                @<div class="item-box">
                    <div class="category-item">
                        <h2 class="title">
                            <a href="@Url.RouteUrl("Category", new { categoryId = item.Id, SeName = item.SeName })" title="@item.PictureModel.Title">
                                @item.Name</a>
                        </h2>
                        <div class="picture">
                            <a href="@Url.RouteUrl("Category", new { categoryId = item.Id, SeName = item.SeName })" title="@item.PictureModel.Title">
                                <img style="border-width: 0px;" alt="@item.PictureModel.AlternateText" src="@item.PictureModel.ImageUrl"
                                    title="@item.PictureModel.Title" /></a>
                        </div>
                    </div>
                </div>
            ))
    </div>
    <div class="home-page-category-grid-separator"></div>
}

I have checked the css , class category-item has got the background image , how can i get different background when each category is added.

Currently I have saved 10 distinct images with the same name as of category in an array & passed the index value of an array to category-item:

<div class="category-item" style="background-image:url('/images/@String.Format("{0}.png",item.Id)');">