JSFiddle - React, Tailwind, and code Playground

HTML

<table>
    <tr id='list'>
        <td>First</td>
        <td>Second</td>
        <td>Third</td>
    </tr>
</table>

CSS

td {
    border: 1px solid black;
    padding: 2px 4px;
}

JavaScript

$('#list').sortable();

// Bind an event when sorting starts
$("#list").bind("sortstart", function(event, ui) {
    
    // Set border colour of cell to red (this works)
    ui.placeholder.css("border", "2px solid red"); 
    
    // Set background colour of cell to red (this doesn't work)
    ui.placeholder.css("background-color", "red");
});