Sign up for Wix or Squarespace and you get exactly what the demo promised: drag a block here, resize a photo there, watch your homepage come together in real time. It's satisfying. Then you switch to the mobile preview, and half of what you built is stacked wrong, overlapping, or spaced like nobody looked at it. Because nobody did, not for that version. You're about to.
This isn't a bug in either platform. It's a second, separate job, and both are upfront about it once you go looking. Wix calls it the Mobile Editor, a real second pass: their own help docs walk you through re-dragging elements and using an "Auto Space on Drag" tool so things don't overlap when you move them, box by box, until a phone screen looks right. Squarespace's newer editor, Fluid Engine, is just as honest: mobile layout gets its own separate editing view, and changes you make there don't touch your desktop design, or the other way around. You can nudge blocks up and down with arrow buttons instead of dragging blind, which helps, but you're still doing the layout work twice.
That's what "you're the designer" actually means once there's more than one screen size to design for. The editor doesn't know how your photo should crop on a six-inch screen or which button belongs under which heading once things stack. You know that. So you tell it. Twice, once per screen size.
Cantrip doesn't have a mobile editor, and that's not a missing feature we're still getting to. There's one version of your page: the text, the images, the sections you picked. The theme's CSS decides how that flows on a phone versus a laptop, the same way it already decides your fonts and your button corners. You're not skipping a step. There isn't a second step to skip.
Here's the honest tradeoff, since that word only means something when it applies to us too: you can't hand-place a photo three pixels over specifically on mobile, or reorder two blocks just for phones and leave desktop alone. If that level of control is what you actually need, a builder with a dedicated mobile mode is the right tool, and Wix and Squarespace both do it well once you're in there doing it. If what you need is a site that looks right on whatever screen your customer happens to be holding, without opening a second editor to check, that's the bet Cantrip makes instead.