WIP: Simplifies and improves table backgrounds

[andresgalante]

This PR is needs more clean up and better organization, but bare with me.

The way we use selectors for background on tables doesn't allow to have a different colors within a row, for example:

    <tr class="table-danger">
        <th scope="row">9</th>
        <td>Column content</td>
        <td class="table-warning">Column content</td>
        <td>Column content</td>
      </tr>

It also doesn't allow to mark something as active like this:

      <tr class="table-danger">
        <th scope="row">9</th>
        <td>Column content</td>
        <td class="table-active">Column content</td>
        <td>Column content</td>
      </tr>

or to mark something as active within an active row like this:

      <tr class="table-active">
        <th scope="row">9</th>
        <td>Column content</td>
        <td class="table-active">Column content</td>
        <td>Column content</td>
      </tr>

... and it produces issues like the one described on #24529

By simplifying the selectors it resolves it and I don't see conflicts with nested tables or .table-striped. I tried to digg up the history of this selector but I couldn't find the root.

@mdo @XhmikosR Can you please point me out what I am missing so I can continue with this PR?

Thanks a lot!

This is a WIP but when it's done it will close #24529

[XhmikosR]

I'm definitely in favor of this, but I always thought there was some specificity reason that led to the current solution. Only @mdo can confirm :)

[mdo]

I think the move from Less to Sass is what broke these selectors. I can't recall any other background on why it's coded the way it is, so I'm definitely open to changing it.

[mdo]

Ah, just read the deleted comment again—these don't work with .table-striped now.

[andresgalante]

@mdo right! I'll work on it

[andresgalante]

@mdo This is a horrible solution, but it fixes the problem.

At the moment a stripe table will overide active states:

And it has all the problems described above.

This horrible selector is needed to get our way around tables when table-stripe is on.

@XhmikosR @mdo can you please take another spin on this one and see what I am missing, or if we can improve the selector

[XhmikosR]

@andresgalante: please be more explicit with what you disable here.

[XhmikosR]

...and here.

[mdo]

Quick update from me—I've been trying to look into this here and there to see what else can be done with our selectors. Still trying, but not a top priority for me or block to v4 stable right now.

[mdo]

Closing as stale and as something to revisit in v5.