A totally ambitious function request

Hi again,

I’ve got a need someone else may need, or someone more code-savvy may be able to help with, so I’m asking publicly.

I want to wrap the <li> items that were modified in the last 30 days with a span tag. ie. if Post X has a modified date of less than 30 days ago, output it wrapped in <span class="recentchange">; if it has a modified date of greater than 30 days ago, leave it alone.

I’ve gotten a little help with this, and what I think is relevant is below. Anyone want to help me out? Thank you!

if((date('U') - get_the_modified_date('U')) <= 2592000) {

https://wordpress.org/plugins/list-category-posts/