Zeno Page Builder support designing page on 3 different screen modes: Desktop, Tablet and Mobile. You can easily change between these modes by using the Screen switcher at the Topbar.
Almost any element style settings (color, font size, font family, ...) support responsiveness.
You can change element setting on a screen, change screen mode and then change setting again, the setting will become responsive on different screen sizes.
You can now switch between screen sizes to confirm it is truly responsive on all screen sizes.
By default, Zeno comes with breakpoints:
Tablet if screen width is smaller than 1025px.
Mobile if screen width is smaller than 720px.
You can change these breakpoints by go to Setting > Breakpoints from the Sidebar.