Background images size

[truegota]

It's probably a dumb question but how big should background images for pages be? Like, if I have a custom page for an RP race and want to have an image showing some of them in the background. Or something like this i.imgur.com/mlHzrxW.jpg
Will it automatically choose the right size if it's big enough or should it be adjusted to the forum?

[elli]

Are you wanting the image to cover the full size of the browser window, or only wrap around main content as shown in your screenshot?

For an image that covers the browser window, the standard is 1920x1080 or smaller with a 16:9 ratio -- an optimized .jpg is best, less than 3MB. You can then use the following CSS to have the image fill the screen completely:

body {
 background: url("images/bg.jpg") no-repeat center center fixed;
 background-size: cover;
}

An image that wraps around content would only need to be wide enough to be visible, and preferably repeating to keep the file size down. Again, an optimized .jpg less than 3MB is best. You can use this CSS:

body {
 background: url("images/bg.jpg") repeat-y center top scroll;
}

Here are some more tips for working with background images -- it has some Wix-specific details, but the concepts still apply: www.wix.com/blog/2015/02/5-golden-tips-for-creating-fullscreen-website-backgrounds/