This issue has been solved. You can also set the 'buttons' to custom the button bar. Make sure to update to the newest version.
<DateBox
ref={el => this.datebox = el}
panelStyle={{ width: 250, height: 300 }}
buttons={(value) => {
return (
<div className="datebox-button f-row" style={{ justifyContent: 'space-between', padding: '5 10px' }}>
<LinkButton plain onClick={() => this.datebox.calendar.moveTo(new Date())}>Today</LinkButton>
<LinkButton plain onClick={() => this.datebox.calendar.selectDate(new Date())}>Ok</LinkButton>
<LinkButton plain onClick={() => this.datebox.closePanel()}>Close</LinkButton>
</div>
)
}}
/>