if you're designing for mobile you can run your localhost connection on your phone
it helps me a lot as sometimes the mobile web viewer in developer tools isn't exactly pixel perfect
to get this working you have to do a tiny bit of config
on a mac go to system preferences > network and then you'll see the message wifi is connected to <name of wifi> and has the IP address <some numbers like 192.354.0.36>
copy the IP address number
then you need to start your server
instead of running rails s run rails s --binding=0.0.0.0
explanation here https://stackoverflow.com/a/29580006
it means that your app will listen to requests from everywhere
to test it out first on your computer, paste the IP address into your browser url field with port 3000
an example
192.354.0.36:3000
if this works you can then put this address into your phones browser and it will work
every time you make edits to your views refresh your mobile browser and you'll see the changes
shout out to Tim for this workflow as he was using it during the portfolio projects