Flow Builder finally matches the rest of the Lightning UI. Winter '27 adds Salesforce Cosmos theme support, the SLDS 2 styling, across the builder.
Where
Throughout the Flow Builder interface, in orgs that use the Salesforce Cosmos theme.
How
There is nothing to configure in the flow itself. With the Cosmos theme active, Flow Builder renders with the SLDS 2 look: rounded buttons with hover feedback and the same modern styling you already see in the regular Salesforce UI. One gap remains: dark mode is not supported in Flow Builder yet.
Why
Until now the builder kept the older look while the rest of the app moved to SLDS 2, so switching between record pages and Flow Builder felt like two different products. The visual change arrives together with the Flow Builder UI refresh, so expect the canvas to look noticeably different after your instance is upgraded.