How to make a circle in CSS on IPhone4?

Question

iPhone

I made the layout, it is displayed well and beautifully on all devices, in the emulator (in the browser) it is displayed beautifully, but on the physical device IPhone 4 / 4s there is a jamb with a circle.
Specially installed Chrome, the same trouble.
Those. cant not only in Safari, but also in Chrome too.
There is a block with a date that is in a circle (border-radius: 50%) and now it is displayed crookedly:

At the same time, it is displayed correctly on all other devices:

UPD: I solved the jamb by setting the minimum width of the block.