def style_plot(figure):
    """Provides basic layout attributes for given figure."""

    figure.update_layout(
        title=f"Relative growth of stock prices for {df.index[0].strftime('%B %Y')} - " \
              +                f"{df.index[-1].strftime('%B %Y')}",
        hovermode="x",
        # D3 formatting. Adds a percentage sign and rounds numbers
        # to 1 decimal after decimal point.
        yaxis1=dict(ticksuffix=" %", tickformat="+.1f", title="Relative growth"),
        yaxis2=dict(
            fixedrange=True,
            overlaying="y",
            range=[0, 1],
            visible=False,
        ),
        xaxis=dict(title="Date")
    )

style_plot(ref_date_fig)