Joining webinar without downloading GoToOpener app

Hello, 

Can you join a webinar using your internet browser only? 

I have seen that when joinig a GoToWebinar one can join just by clicking on the Join button in the invitation, without a need to download the GoToOpener app. How to do this?

Also, how to get a newer, more modern design, GoToWebinar? Some webinars I join have a modern design but when I organise a webinar the graphics and design in general look like from 70s... I have a paid version. 

Thanks in advance for help. 

Nikola