Encode Small Images in Stylesheets

Continuing the earlier theme of Optimizing Images to Save Bandwidth and Speed Page Load, you can also encode small (background) images directly in your stylesheets. For each image / page element encoded within a stylesheet, it means one less HTTP connection for content, which in turn means pages finish loading faster. These images should generally be small and downloadable quickly — what you want to save is the HTTP connection overhead, not the download time (both images and stylesheets are generally cached after downloading). The images should also be encoded within sourced stylesheet files, so the stylesheet files can be cached by the browser. If you encode images within your content (using <style></style> tags for example), the encoded image will have to be downloaded for every page view, so although you’re saving HTTP connections, your page size has increased. By encoding images in sourced stylesheet files instead, the browser (and content delivery services) can cache the whole stylesheet, including the encoded image(s).

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