我的主题图像不响应WordPress版本4.4.2

I really appreciate the help I get from this community.

Here is my question: I am developing a theme for my self and running WordPress version 4.4.2 on my computer using MAMP. The images I upload to my posts and pages are not coming out responsive. I read that WordPress version 4.4 supports responsive images out of the box.

NOTE: I have not set images sizes or added any code or function that is realted to images on my functions.php file besides:

add_theme_support('post-thumbnails');

see screen shot.

enter image description here

Modify functions.php to generate more image sizes

Every time you upload an image WordPress saves it at its native size. It also automatically generates 3 resized copies in these standard sizes (either height or width may change based on image ratio):

  • Thumbnail (150×150)
  • Medium (300×300)
  • Large (1024×1024)

This is done by modifying the functions.php file. To add new image sizes, you need to add calls to the add_image_size function. Here’s an example that adds four new image sizes:

add_image_size( 'sml_size', 300 ); 
add_image_size( 'mid_size', 600 ); 
add_image_size( 'lrg_size', 1200 ); 
add_image_size( 'sup_size', 2400 );

And I got some reference in this URL. If you want try this too

Link for reference

img{max-width: 100%;height: auto;} - and combine it with add_image_size. You should not post full size image it thubnails