discourse/app/assets/stylesheets/common/base/history.scss

// styles that apply to the popup that appears when you show the edit history of a post

.modal.history-modal {
  #revision-numbers {
    display: inline-block;
    min-width: 100px;
    text-align: center;
  }
  #revision-loading {
    .fa {
      margin-right: 7px;
    }
  }
  ins, .diff-ins {
    code, img {
      border: 2px solid $success;
    }
    img {
      opacity: .75;
      filter: alpha(opacity=75);
    }
    a {
      color: $success;
      text-decoration: none;
    }
  }
  img.diff-ins, code.diff-ins {
    border: 2px solid $success;
  }
  img.diff-ins {
    opacity: .75;
    filter: alpha(opacity=75);
  }
  .diff-ins {
    background: scale-color($success, $lightness: 90%);
  }
  ins {
    color: $success;
    background: scale-color($success, $lightness: 90%);
  }
  del, .diff-del {
    code, img {
      border: 2px solid $danger;
    }
    img {
      opacity: .5;
      filter: alpha(opacity=50);
    }
    a {
      color: $danger;
      text-decoration: none;
    }
  }
  img.diff-del, code.diff-del {
    border: 2px solid $danger;
  }
  img.diff-del {
    opacity: .5;
    filter: alpha(opacity=50);
  }
  .diff-del {
    background: scale-color($danger, $lightness: 60%);
  }
  del {
    color: $danger;
    background: scale-color($danger, $lightness: 60%);
  }
  span.date {
    font-weight: bold;
  }
  span.edit-reason {
    background-color: lighten($highlight, 23%);
    padding: 3px 5px 5px 5px;
  }
  .fa-ban {
    color: #f00;
  }
  .hidden-revision {
    opacity: 0.5;
  }
}