By default, the XControls try to mimic the look and feel of a native application. This behavior can be modified by changing the attributes of the CSS files.
Among others, the XControls use these 3 CSS files:
1. unp/css/bootcards-desktop.min.css for desktop browsers such as Chrome
2. unp/css/bootcards-ios.min.css for iOS devices
3. unp/css/bootcards-android.min.css for Android devices
By changing the values of the properties of the "form-control" CSS class, in these files, one can customize the borders displayed around input boxes.