Hello Štěpán,
This is a known issue occurring in Cordova-based applications. There are various discussions on the internet about the Android soft keyboard hiding input elements near the bottom of the app. The most reliable solution seems to be scrolling the page manually to the focused input. To do this you can either set a timeout on focusing the input, as suggested here:
Phonegap Android keyboard covers input elements scrolling is disabled
or instead of using a timeout, use the custom Keyboard plugin to capture the keyboard show and hide events to perform the scrolling:
Keyboard Plugin
Regards,
Tsvetina
Telerik