Install something like https://chrome.google.com/webstore/detail/stylish-custom-themes-for/fjnbnpbmkenffdnngjfgmeleoegfcffe extension, insert this style:

.post-listing {
    border-radius: 10px;
    padding: 10px;
  	background-color: #23252f;
}

body {
  background-color: #282937;
}

.navbar {
  background-color: #23252f;
}

.vote-bar {
      display: flex;
    align-items: center;
    justify-content: center;
    flex-direction: column;
}

.card-body {
  background-color: #23252f;
}

.border-secondary {
      border: 1px solid #1a1c23 !important;
}

I think it looks a bit better, inspired by Dracula theme