Style issues

Hi,

please try with the code below.

For sidebar replace this CSS:

body.wp-night-mode-on .sidebar {
    background-color: #202020;
}

with this one:

body.wp-night-mode-on .sidebar * {
    background-color: #202020;
}

and you will probably want to replace margin with padding from sidebar header, something like this:
from:

@media screen and (min-width: 59.6875em) {
  .site-header {
      background-color: transparent;
      border-bottom: 0;
      margin: 20% 0;
      padding: 0 20%;
  }
}

to:

@media screen and (min-width: 59.6875em) {
  .site-header {
      background-color: transparent;
      border-bottom: 0;
      margin: 0 0;
      padding: 20% 20%;
  }
}

For the main content part, replace this:

body.wp-night-mode-on .entry-header {
    background-color: #202020;
}

body.wp-night-mode-on .entry-content {
    background-color: #202020;
}

body.wp-night-mode-on .site-footer {
    background-color: #202020;
}

with this one:

body.wp-night-mode-on .entry-header,
body.wp-night-mode-on .entry-header * {
    background-color: #202020;
}

body.wp-night-mode-on .entry-content,
body.wp-night-mode-on .entry-content * {
    background-color: #202020;
}

body.wp-night-mode-on .site-footer * {
    background-color: #202020;
}

This is it 🙂
Please let me know if this helped you.