axis definition: convert remaining double fields to Measures, set default label padding to 0.8rem

    mode(AxisMode::AUTO),

    label_placement(AxisLabelPlacement::OUTSIDE),

    label_formatter(format_decimal_fixed(1)),

    label_padding_rem(1.0f),

    label_font_size_rem(1.0f),

    tick_length_rem(0.4f) {}

    label_padding({Unit::REM, 0.8f}),

    label_font_size({Unit::REM, 1.0f}),

    tick_length({Unit::REM, 0.4f}) {}

ReturnCode parseAxisMode(

    const std::string& str,

        target,

        x,

        y,

        x + from_rem(*target, axis_config.tick_length_rem) * label_placement,

        x + to_px(target->measures, axis_config.tick_length).value * label_placement,

        y,

        style);

  }

  /* draw labels */

  auto label_padding = from_rem(*target, axis_config.label_padding_rem);

  auto label_padding = to_px(target->measures, axis_config.label_padding).value;

  for (const auto& label : axis_config.labels) {

    auto [ tick, label_text ] = label;

    auto sy = y0 + (y1 - y0) * (1.0 - tick);

        x,

        y,

        x,

        y + from_rem(*target, axis_config.tick_length_rem) * label_placement,

        y + to_px(target->measures, axis_config.tick_length).value * label_placement,

        style);

  }

  /* draw labels */

  auto label_padding = from_rem(*target, axis_config.label_padding_rem);

  auto label_padding = from_rem(*target, axis_config.label_padding);

  for (const auto& label : axis_config.labels) {

    auto [ tick, label_text ] = label;

    auto sx = x0 + (x1 - x0) * tick;

  Colour text_colour;

  Colour border_colour;

  FontInfo font;

  double label_padding_rem;

  double label_font_size_rem;

  double tick_length_rem;

  Measure label_padding;

  Measure label_font_size;

  Measure tick_length;

};

ReturnCode parseAxisMode(