How do I change the class for this input element?

I am not being able to change the class of input in views-box_checkout_cart.inc.php on line 51

 
I want to add a different class to the one it has but I can't, I tried with the 'class="quantity-selector"' but it still doesn't appear in the source code

views-box_checkout_cart.inc.php sounds like a file found in the vmods/.cache/ folder. It's the outcome of a modification that goes in that folder.

The decimal field is cooked here:
https://github.com/litecart/litecart/blob/2.5.4/public_html/includes/functions/func_form.inc.php#L190
In the last parameter named $parameters you can pass 'class="somethingelse"'.

<?php echo !empty($item['quantity_unit']['decimals']) ? functions::form_draw_decimal_field('item['.$key.'][quantity]', $item['quantity'], $item['quantity_unit']['decimals'], $item['quantity_min'], $item['quantity_max'], ($item['quantity_step'] ? 'step="'. (float)$item['quantity_step'] .'"' : '') . ' class="somethingelse"') : functions::form_draw_number_field('item['.$key.'][quantity]', $item['quantity'], $item['quantity_min'], $item['quantity_max'], ($item['quantity_step'] ? 'step="'. (float)$item['quantity_step'] .'"' : '') . ' class="somethingelse"'); ?>

I should polish this code for a future version.

[url=https://github.com/litecart/litecart/blob/1965f68c7795b052d58a950f8b1e91f2cfb1ea13/public_html/includes/templates/default.catalog/views/box_checkout_cart.inc.php#L51]https://github.com/litecart/litecart/blob/1965f68c7795b052d58a950f8b1e91f2cfb1ea13/public_html/includes/templates/default.catalog/views/box_checkout_cart.inc.php#L51[/url]
 On this line I want to add a unique different class to this input, I already cleared the cache and it does not show. On line 54 I could add the class by replacing the 'style="width: 125px;"' x the class but on line 51 I cannot find the way to add

Can you not just address the field with an element property identifier?

  background: orange;
}```

It sounds overly complex to change this to a unique class.

[quote]I already cleared the cache and it does not show.[/quote]
Did you see in the conditions there are 4 different ways this field is output? 4 places to modify.