Official site offers unavailable software to install for unsupported OSs.
Well, I'm on Mountain Lion, and I just knew about this browser, so I made my mind to try this new browser. I installed dmg from the official download button, then opened it and copied it to App folder. I had no problem here, but when I open the browser, it says "your OS is not supported". What? Then why you didn't say it first; just after clicking download button? Pls stop cheating us, and I hope they correct the system about download.
https://vivaldi.com/download/ (scroll down) shows Mac 10.9 and newer.
@Gwen-Dragon Vivaldi really should display the system requirements (or provide a link to them) under their main download button on vivaldi.com. Mac users visiting the main web site immediately see two download buttons (one in the middle of the page and another on the upper right) and both are links to the .dmg install image. The last Download link, toward the bottom of the page, doesn't list OS X 10.9 as a minimum requirement either. To a new prospective user, it provides the impression that Vivaldi is ready to install on their system. Unless they're also looking for a Windows or Linux installer, it's unlikely that they'll click on the "Download Page" link where the system requirements are shown.
This information is particularly of interest to people with older systems. Many are of them are actively seeking a new web browser because their current browser is no longer providing updates for their system.
Sorry, i try to tell this one of the webdevs of vivaldi.com.