This software lets you map your local stylesheets to a live site, so you don't need to upload new css every time you make a small change. Ask christian@beru.dk for a serial number so you don't just have a trial.
Download the software, and do this if you're on a Mac: SSL Charles Proxy mac fix
Start mapping your stylesheet
If the site on which you want to show your local stylesheet uses HTTPS, you have to add it to a list of URL's inside the program first. You only do this once per site. Go here (or right-click on the site on choose "Enable SSL Proxying"):

And add the desired URL:

Click OK and start recording inside the program:

Go to the live site and add /?debug=true after the url:

Now, go back into Charles and you will see a long list of URL's. Find the one that you added in the SSL settings, and find this specific file. You might need to update the site a few times while recording to see the following directory:

Right click on theme.css, click "Map local" and choose the corresponding file on your own computer inside the theme. Now, when you make changes to your scss files and theme.css compiles, you can see the changes inside your browser when you update the site.
If you want to toggle local mapping on/off, click here:

This mapping can be done for JS files, images, icons etc.