Here are the details. Opera One Browser Adds Vertical Tabs – Should Safari Follow?.
Opera One browser just pushed an update adding a Vertical Tabs option that moves the tab bar from the top of the window to a resizable panel down the left-hand side. The feature aims to solve the perennial horizontal tab problem where too many open tabs makes each one shrink to an unreadable sliver of the webpage’s favicon. By contrast, in the vertical layout, page titles always stay legible. Opera’s existing Tab Islands feature – where tabs that came from the same page or browsing session are grouped into a collapsible section in the tab strip – carries over from the standard view, and the panel collapses when screen space is tight.
Opera has also built Google Lens directly into the.

