Currently I use the browser's dev tools and that allows me to pretty much do the same thing as this tool (I've got the CSS properties memorized at this point).

Currently I use the browser's dev tools and that allows me to pretty much do the same thing as this tool (I've got the CSS properties memorized at this point). I probably won't use this, but kudos to you for putting in all that work! I did find your tool intuitive to use, nice job. An awesome feature to have is the ability to resize (and specify the size of) the template window so we could test responsive design and different device sizes.