CSS - Image sprites overusing

I have recently begun using image sprites and they are definately great for reducing http requests. Is there a point where it becomes bad practice?

Im thinking particularly where a lot of extra markup has to be added to support them. For example, using them for list bullet points, I have to add two or three extra spans to get everything alligned etc.

Theres also the annoying point that you cant use repeating images, so therfore there is always the toss up between one large image as part of sprite or a tiny 1 pixel image used for repeating downloaded on its own.

Im re开发者_开发技巧ally looking for an opinion on the two situations outlined here + any other general considerations/guidelines for using sprites.

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They can often cause performance issues on mobile devices. I'm not 100% certain why (never really dived into the problem), but I'm assuming it's because the mobile webkit is loading a new copy of a relatively large image into memory for every instance of it on the page. Since mobile devices often have very small amounts of RAM, it can quickly cause the page to slow down.

I've run into this issue before when having about 300 "icon" sprites on a page at one time, each pulling from a sprite image that contained about 50 different icons. Going back to "normal" methods of one icon per image (or 2-3 for hover states) solved performance issues on this particular page.

Also, many browsers (mobile and otherwise) will often not 100% respect the clipping of sprites when you slightly resize the page content (e.g. using "Zoom In/Out" on the browser itself). You'll often see little pieces of the sprite next to the one you want to use.

As for your bullet example, you shouldn't ever need more than one extra div/span. You would set a margin-left on the li and position your "bullet div" in the empty space it creates.

That being said, I use sprites all the time because they're convenient, just be aware of a few issues with them. Generally, I have sprites.png, sprites_h.png and sprites_v.png for horizontally and vertically repeating pieces.

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Write two simple test pages, use sprites on one, and not on the other. Use a tool like http://www.webpagetest.org/ to measure the performance in a few different browsers. Once you have data, you can make decisions.

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I would divide sprites by related elements, like navigation and content-related sprites, so you can benefit from sprites and keep a logical order in your code. Don't forget that readable and understandable code should be a priority (particularly with CSS, it can get very messy) unless you're working on a Google-scale project.