CSS and custom tags

doctorbill used Ask the Experts™
A CSS question:

Let's take the <td> tag as an example

Is it possible to make a custom css tag and use that to dictate the styling of any <td> tags inside it
css page:
customtag > td
some condition
php page:
<customtag><td> text </td></customtag>

The reason for this is that I want to add a specific condition to a set of <td> tag's which already have defined css conditions defined for that particular tag in the css page in the rest of the php page
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Terry WoodsIT Guru
Most Valuable Expert 2011

Why a custom tag and not just a <div> tag with a particular class, or for that matter, why not just add a class or id to an element on the page?
Terry WoodsIT Guru
Most Valuable Expert 2011

This may be of interest: https://stackoverflow.com/questions/5970093/using-custom-html-tags

The top 2 answers are worth a read. Long story short, if you create a custom tag, it should probably work, but it sounds like it's a good idea to ensure you put a hyphen character in the tag name (eg <my-tag>) to avoid the risk of the tag become a standard one in future.
David FavorFractional CTO
Distinguished Expert 2018

You can add anything you like to your CSS.

However, for your custom tag to be processed, you'd somehow have to convince every visitor to your site to download some sort of hacked version of their browser, which you coded to process your custom CSS tag.

Highly unlikely approach to whatever you're trying to solve.

Just use CSS classes or style by element ID.
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Most Valuable Expert 2018
Distinguished Expert 2018
A <tr> is the only permitted parent of a <td> so custom tags (or any other) would not be valid. You can add selectors (such as a class or ID) to either the <td> elements themselves or to any parent element and then use that to limit the CSS applied.

<table class="custom">
<td>Cell 1</td>
<td>Cell 2</td>

.custom td { color: red; }


Thanks all
Brandon LyonWeb Developer/Designer

Just to clarify a bit of misinformation earlier in the thread, custom elements are possible. That said I wouldn't suggest using them in situations where a classname, id, or attribute would work just as well.

Here is a tutorial about custom elements https://blog.teamtreehouse.com/create-custom-html-elements-2

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