title: How can I let users customize background images?
body: <p>Many sites these days have 'theming' functionality, when user is able to customize the pages' look. Sometimes it's only a fixed set of themes, but sometimes people are free to choose any style they want - for example, they can set up any color of the pages' background.</p>
  
  <p>I want to go a step further - and let them choose the background <em>image</em> as well. The flow is very simple: user uploads a file (via <code>&lt;input type="file" /&gt;</code>), then this file becomes a background image - but only for this user. </p>
  
  <p>I can't find anything about this functionality online, though, and I have no clue about what to do.</p>
  
  <p>Something else I was thinking was that, if a user selects a background, maybe I could use HTML5 <code>localstorage</code> to make that background come up every-time that visitor visits the page.</p>