Environment

• Package version(s): 3.0.1
• Browser and OS versions: Chrome 67.0.3396.99 (Official Build) (64-bit)

Steps to reproduce

Add a popover to a button that is inside a control group

 <ControlGroup>
    <Popover content={<p>Hello</p>}>
        <Button text="Open"/>
    </Popover>
    <Button icon="cross"/>
</ControlGroup>

Actual behavior

Border radius is not inherited by components wrapped in a popover, eg <Select />, <Button />

Expected behavior

Components should inherit border radius based on their position in the ControlGroup

Possible solution

Add border-radius: inherit to popover-target and popover-wrapper when inside a control group