How to move the sidebar in TwentyFifteen to the right?

Question

Is it possible to move the sidebar in the TwentyFifteen theme to the right using a child theme and CSS only, or does it require changes to the theme itself? The main issue I'm running into is that I can get the sidebar on the right side in either the "default" or the "scrolled" scenario, but not in both (default uses position: relative and is what you get when the page loads, scrolled is set when the page is scrolled and changes the sidebar position to absolute.)

Answer 1

I took the following from the rtl.css and applied them via Magic Widget with additional !important keywords to an English site:

body:before {
    right: 0 !important;
    left: auto !important;
}
.sidebar {
    float: right !important;
    margin-right: auto !important;
    margin-left: -100% !important;
}
.site-content {
    float: right !important;
    margin-right: 29.4118% !important;
    margin-left: auto !important;
}
.site-footer {
    float: right !important;
    margin: 0 35.2941% 0 0 !important;
}

This seems to work, even when you scroll down.

Answer 2

You can add below code to your child theme.

@media screen and (min-width: 59.6875em) {
    .site-content {
        float: left;
        margin-left: 0px;
        width: 70.5882%;
    }   
    .sidebar {
        float: right;
        right:0;
        margin-right: 0px;
        max-width: 413px;
        width: 29.4118%;
    }   
    body:before {
        right: 0;
        left:auto;
    }       
    .site-footer {
        margin: 0 0 0 6.1%;
    }
}

Answer 3

The accepted solution breaks the responsiveness of the theme when used from a mobile. I had to wrap the accepted solution by toscho and Anteru in a @media screen as the original twentyfifteen template.

@media screen and (min-width: 59.6875em) {
  body:before {
    right: 0 !important;
    left: auto !important;
  }

  .sidebar {
    float: right !important;
    margin-right: auto !important;
    margin-left: -100% !important;
  }
  .site-content {
    float: right !important;
    margin-right: 29.4118% !important;
    margin-left: auto !important;
  }
  .site-footer {
    float: right !important;
    margin: 0 35.2941% 0 0 !important;
  }

  body { direction: rtl; }
  .sidebar, .site-content, .site-footer { direction: ltr; }
}

Answer 4

I recently extended a child theme from tips and tricks for the twenty fifteen theme and i thought i should share how you can move the sidebar to the right with you guys. in the extended child theme i removed the sidebar completely from the twenty fifteen theme as some people prefer to use it that way. You can download the child theme here and change the code to restore the sidebar to the right:

Change the following code:

.sidebar {
    float: none !important;
    margin-right: 0px;
    max-width: 413px;
    position: relative !important;
    width: 29.4118%;
    background: #fff;
    box-shadow: 0 0 1px rgba(0, 0, 0, 0.15);
    display: none;
}

to

.sidebar {
    float: right;
    margin-right: 0px;
    max-width: 413px;
    position: relative !important;
    width: 29.4118%;
    background: #fff;
    box-shadow: 0 0 1px rgba(0, 0, 0, 0.15);
}