       oFragColor = get_fragment_color(distanceFromMixLine, pixelsPerFragment);
 
       if (vRadii.x > 0.0) {
-        float alpha = alpha_for_solid_border_corner(localPos, vRadii.z, vRadii.x, pixelsPerFragment);
+        float alpha = alpha_for_solid_border_corner(localPos, vRadii.zw, vRadii.xy, pixelsPerFragment);
         oFragColor *= vec4(1.0, 1.0, 1.0, alpha);
       }
 

                                         float pixels_per_fragment) {
  float total_border_width = vRadii.x - vRadii.z;
  float one_third_width = total_border_width / 3.0;

  // Contribution of the outer border segment.
  float alpha = alpha_for_solid_border_corner(local_pos,
                                              vRadii.x - one_third_width,
                                              vRadii.x,
                                              pixels_per_fragment);

  // Contribution of the inner border segment.
  alpha += alpha_for_solid_border_corner(local_pos,
                                         vRadii.z,
                                         vRadii.z + one_third_width,
                                         pixels_per_fragment);
  return get_fragment_color(distance_from_mix_line, pixels_per_fragment) * vec4(1.0, 1.0, 1.0, alpha);
}

      oFragColor = get_fragment_color(distance_from_mix_line, pixels_per_fragment);
      if (vRadii.x > 0.0) {
        oFragColor *= vec4(1.0, 1.0, 1.0, alpha_for_solid_border_corner(local_pos,
                                                                  vRadii.zw,
                                                                  vRadii.xy,
                                                                  pixels_per_fragment));
      }

