Captions should be responsive

[maxwell.shim]

Problem 1 : Does not resize image with caption for a responsive design.

Returns the fixed width of the image function img_caption_shortcode()
So does not change the image width.

I think change style max-width.

return '<div ' . $id . 'class="wp-caption ' . esc_attr($align) . '" style="max-width: ' . (10 + (int) $width) . 'px">'

[DrewAPicture]

Modifying img_caption_shortcode() isn't necessary.

The same effect can be achieved by adding max-width: 100%; to .wp-caption in your theme's stylesheet. In fact, the Twenty Twelve theme does it this way, see [21407].

Sorta Related: #10409