Photos in post distorted when viewed with smartphone

Newest WP version, newest NG version, Twenty-Eleven Theme

With NextGEN you can add a picture from one of your galleries directly into your post. I think everybody knows that!

There has been a problem for years that on smaller screens (Smartphone) the pictures get distorted. We talk only about the picture directly added into a post, not about viewing the gallery itself.

In my case the problem appears with diagonal photos, not with the vertical ones. A diagonal photo in an article will not be displayed proportional with the smartphone. The picture will be displayed as a square!

For the last five years I did not care about this problem, because there was a simple solution.

I just went into the style.css of my page and found this part:

.wp-caption img {
display: block;
max-width: 98%;
max-width: calc( 100% – 14px );

I had to change it to:

.wp-caption img {
display: block;
max-width: 100%;
height: auto;

After doing this everything worked fine! After every theme update I had to do it again, because the theme-update changed the style.css back to normal.

But after the latest update it does just not do the trick anymore.

The style.css is now editor-style.css and there are new variables like margin.
No matter if i delete the new variables or not:
Changing the wp-caption img part to the good old….

.wp-caption img {
display: block;
max-width: 100%;
height: auto;

…. does not have any effect anymore ??

When someone visits my page with a smartphone, all gallery pictures integrated into an article look like junk.

What can I do to make them display proportional again?

Greetings,

SFrueh

The page I need help with: [log in to see the link]