Card-mod themes and lovelace YAML mode, not sure how to select a class

Trying to git gud at this, but super confused. I’m breaking apart my super bloated dashboard to reuse code and make it easier to modify by creating a theme around it with variables.

So for example, I have entities cards that wrap many others at the top level, to give them a title mostly and I do it like this:

type: entities
card_mod:
  class: card-wrapper
title: Lampar
show_header_toggle: false

And in the theme file:

  card-mod-card: |
      .card-wrapper {
        width: var(--ha-width) !important;
        margin: 0 auto;
        font-weight: var(--header-weight);
        font-size: var(--header-font-size);
        background: none;
        border: none;
      }  

And I guess this is fine? Please correct me if I’m wrong.

But then I get to more complicated cards like our shopping list (todo integration), where I’ve previously styled a lot of different elements with card_mod. Using pretty generic selectors in card_mod was fine, but now I’m sure I’m doing something wrong:

    entities:
      - type: custom:hui-todo-list-card
        entity: todo.innkaupalisti
        title: ''
        card_mod:
          class: todo-list

Ok all good so far? But then on the other side, in the theme file, I have no idea how to explicitly select all of the elements I was styling before, and I’m sure it can’t be right just to paste something super generic like this under card-mod-card:

      ha-card.todo-list {
        background: var(--list-gradient) !important; 
        border: none;
        padding-bottom: 20px;
      }     
      div.header {
        display: none;
      }
      .divider {
          display: none;
      }

The first definition is fine, ha-card.todo-list, it’s this list and no other, but then I have no idea how to select the other two properly. I hope I’m making myself clear. The very short documentation on this and my knowledge are to far apart to gel…