message: Improve default style of `Button`
diff: @@ -70,12 +70,12 @@ struct Default;
  impl StyleSheet for Default {
  fn active(&self) -> Style {
  Style {
  - shadow_offset: Vector::new(0.0, 1.0),
  - background: Some(Background::Color([0.5, 0.5, 0.5].into())),
  - border_radius: 5,
  - border_width: 0,
  - border_color: Color::TRANSPARENT,
  - text_color: Color::WHITE,
  + shadow_offset: Vector::new(0.0, 0.0),
  + background: Some(Background::Color([0.87, 0.87, 0.87].into())),
  + border_radius: 2,
  + border_width: 1,
  + border_color: [0.7, 0.7, 0.7].into(),
  + text_color: Color::BLACK,
  }
  }
  }
  