custom css confusion

Hi,

I am using a sub theme and as per instructions I have a styles.css sheet inside my custom folder. As I understand this is used to have my css overrides.

You were kind enough to provide me the code colors as per https://www.drupal.org/node/2919583#comment-12320907 →

I pasted that css in the styles.css sheet and as a test changed the background color of the second footer div to red:

#footer-container .first-footer > div {
  background-color: #3c457d;
}

That worked fine but upon trying to change the background color of the first second footer div to blue the css did not apply, even after clearing cache:

#footer-container .first-footer > div {
  background-color: #3c457d;
}

Am I overlooking something because changing e.g. header background color works also.