For a design tool Customily is missing a really key component to design which is being able to properly space and align items. All the headache of trying to have multiple things line up and be spaced evenly would be solved with rulers, guides and grids. At the very least there should be a grid. I feel like this would be super easy to implement. A light grey grid instead of just the white background.

If you really want to kick things up a notch I highly recommend a snap to grid or snap to guide function. I spend so much time trying to manually line things up.

The example is from Adobe Illustrator