Wrong render of soc.media web part
Just visited http://openid.net/2016/09/13/harmonizing-ietf-scim-and-openid-connect-enabling-oidc-clients-to-use-scim-services/ . That page / site uses a social media block that Vivaldi renders in such a way it overlaps with the main text. I checked in Firefox: FF renders that soc.media part more vertically stretched so it doesn't overlap the main text.
For me, that social media block is floating to the left of the main text (even if I resize the window) as it should. I tried both 1.6.689.40 Stable and the most recent internal build of Vivaldi.
Which version are you using and is it possible that you have an extension installed that changes the layout of the page?